Search Results

Search found 1848 results on 74 pages for 'printf'.

Page 34/74 | < Previous Page | 30 31 32 33 34 35 36 37 38 39 40 41  | Next Page >

  • Is apparent NULL pointer dereference in C actually pointer arithmetic?

    - by karthik A
    hey ive got this piece of code. It dereferences a null pointer here. But then there is an and with unsigned int. I really dont understand the whole part. Can someone explain the output.?? struct hi { long a; int b; long c; }; int main() { struct hi ob={3,4,5}; struct hi *ptr=&ob; int num= (unsigned int) & (((struct hi *)0)->b); printf("%d",num); printf("%d",*(int *)((char *)ptr + (unsigned int) & (((struct hi *)0)->b))); } The output I get is 44. But how does it work?

    Read the article

  • The glutKeyboardFunc does not react to key presses immediately

    - by Nibirue
    I have a function glutKeyboardFunc(keyboard), where keyboard has: void keyboard(unsigned char key, int x, int y){ float alpha = 1.0; switch(key){ case 'c': glClearColor(1,0,0,alpha); printf("success"); break; } } This is a summary of the function; it works properly, but only once some other action has occurred. For instance, the printf statement reports success immediately on keystroke 'c', but the background color does not become active until I click somewhere else on the canvas. I want all keystrokes to have an immediate effect.

    Read the article

  • counting characters program in c

    - by mena
    Hello, the output of characters number is the actual no. plus 3 i don't know why? This is the code: void main(void) { int ch,w=0,c=0; do { ch=getche(); ++c; if(ch==32) { ++w; ++c; } }while(ch!=13); printf("\nnum of characters is %d",c); printf("\nnum of words is %d",w); getch(); }

    Read the article

  • Method sscanf() ambiguous behavior

    - by Carmen Cojocaru
    I am trying to understand how sscanf() works. I ran some examples from this page: http://docs.roxen.com/pike/7.0/tutorial/strings/sscanf.xml and they don't work on my platform. I can't understand why. For instance: "sscanf("4711bar", "%d%s", a, b);" makes the program exit with an error... Here is one of the examples that work: "sscanf("foo", "f%s", a);". Does anybody know why? Do they work on your platforms? Thank you. This is my code: int main(void){ char *b = (char*)malloc(sizeof(char)*100); int a = 0; sscanf("4711bar", "%d%s", a, b); printf("%d", a); printf("%s", b); }

    Read the article

  • pthread_exit return value

    - by Manty
    This is surprising for me. void * thread_func(void *arg) { pthread_exit(&ret); } int main(void) { pthread_t thr; int *exit_status; pthread_create(&thr, NULL, thread_func, NULL); sleep(2); pthread_join(thr, (void **)&exit_status); printf("value of exit status - %d\n", *exit_status); ret = 20; pthread_join(thr, (void **)&exit_status); printf("value of exit status - %d\n", *exit_status); return 0; } The output is value of exit status - 50 value of exit status - 20 I was expecting both the times the exit_status would be the actual exit value(50 in my case) of the thread. Instead it is just returning the value of the global variable which I used for pthread_exit. Is it not a bug?

    Read the article

  • C++: Throwing shared_ptr of derived and catching shared_ptr of base?

    - by hasvn
    Ok, I've been told this problem: Why can you throw a pointer to a derived class and catch a pointer to its base... but you can't do that with shared_ptrs? Example, this works: class Base {}; class Derived : public Base {}; int main() { try { throw new Derived() ; } catch( const Base2 * b ) { printf("Received a base" ) ; } return 0 ; } But this doesn't int main() { try { throw std::tr1::shared_ptr<Derived>( new Derived() ) ; } catch( const std::tr1::shared_ptr<Base> & b ) { printf("Received a base" ) ; } return 0 ; } Any ideas?

    Read the article

  • bandwidth throttling C linux

    - by bob moch
    hi im currently creating a function to create a sleep time i can pause between packets for my port scanner im creating for personal/educational use for my home network. what im currently doing is opening /proc/net/dev and reading the 9th set of digits for the eth0 interface to find out the current packets being set and then reading it again and doing some math to figure out a delay to sleep between sending a packet to a port to identify it and fingerprint it. my problem is that no matter what throttle % i use it always seems to send the same rate of packets. i think its mainly my way of mathematically creating my sleep delay. edit:: dont mind the function declaration and the struct stuff all im doing is spawning this function in a thread and passing a pointer to a struct to the function, recreating the struct locally and then freeing the passed structs memory. void *bandwidthmonitor_cmd(void *param) { char cmdline[1024], *bytedata[19]; int i = 0, ii = 0; long long prevbytes = 0, currentbytes = 0, elapsedbytes = 0, byteusage = 0, maxthrottle = 0; command_struct bandwidth = *((command_struct *)param); free(param); //printf("speed: %d\n throttle: %d\n\n", UPLOAD_SPEED, bandwidth.throttle); maxthrottle = UPLOAD_SPEED * bandwidth.throttle / 100; //printf("max throttle:%lld\n", maxthrottle); FILE *f = fopen("/proc/net/dev", "r"); if(f != NULL) { while(1) { while(fgets(cmdline, sizeof(cmdline), f) != NULL) { cmdline[strlen(cmdline)] = '\0'; if(strncmp(cmdline, " eth0", 6) == 0) { bytedata[0] = strtok(cmdline, " "); while(bytedata[i] != NULL) { i++; bytedata[i] = strtok(NULL, " "); } bytedata[i + 1] = '\0'; currentbytes = atoi(bytedata[9]); } } i = 0; rewind(f); elapsedbytes = currentbytes - prevbytes; prevbytes = currentbytes; byteusage = 8 * (elapsedbytes / 1024); //printf("usage:%lld\n",byteusage); if(ii & 0x40) { SLEEP += (maxthrottle - byteusage) * -1.1;//-2.5; if(SLEEP < 0){ SLEEP = 0; } //printf("sleep:%d\n", SLEEP); } usleep(25000); ii++; } } return NULL; } SLEEP and UPLOAD_SPEED are global variables and UPLOAD_SPEED is in kb/s and generated via a speedtest function that gets the upload speed of my computer. this function is running inside a POSIX thread updating SLEEP which my threads doing the socket work grab to sleep by after every packet. as testing instead of only doing the ports i want to check i make it do all the ports over and over again so i can run dstat on a machine to check bandwidth and no matter what bandwidth.throttle is set to it always seems to generate the same amount of bandwidth to the dstat machine. the way i calculate how much i "should" throttle by is by finding the maximum throttle speed which is defined as maxthrottle = upload_speed * throttle / 100; for example if my upload speed was 1000kb/s and my throttle was 90 (90%) my max throttle would be 900kb/s from there it would find the current bytes sent from /proc/net/dev and then find my sleep time via incrementing or decrementing it via sleep += (maxthrottle - bytesysed) * -1.1; this should in theory increase or decrease the sleep time based on how many bytes used there are. the if(ii & 0x40) statement is just for some moderation control. it makes it so it only sets sleep to a new time every 30-40 iterations. final notes: the main problem is that the sleep timer does not seem to modify the speed of packets being set. or maybe its just my implementation because on a freshly restarted machine where /proc/net/dev has low numbers of bytes sent it seems to raise the sleep timer accordingly on my 60kb/s upload machine (ex if i set the throttle to 2 it will incline the sleep timer until network bandwidth out reaches the max bandwidth threshold, but when i try running it on a server which as been online forever it doesnt seem to work as nicely if at all. if anyone can suggest a new method of monitoring the network to adjust a sleep delay then let me know or if anyone sees a flaw in my code. thank you.

    Read the article

  • Filter Phrase Query

    - by alsuelo
    I try to filter a phrase to make a search in my website i've this query, this code working with one word but when i type wit more than one isn't working becuase the print is without spaces. $phrase = $this->getState($this->context.".filter_phrase"); printf("Original string: %s\n", $phrase); if(!empty($phrase)) { $escaped = $db->escape($phrase, true); printf("Escaped string: %s\n", $escaped); $quoted = $db->quote("%" . $escaped . "%" , false); $query->where ('a.title LIKE ' .$quoted); } Example i type king and the output is king , when i type the king the output is theking, i want to know if exist any way to conserve the blank spaces.

    Read the article

  • c permutation of a number

    - by Pkp
    I am writing a program for magic box. As the only way around it is brute force, I wrote a program to compute permutations of a given array using bells algorithm. I wrote in the lines similar to http://programminggeeks.com/c-code-for-permutation/. It does work for array of 3 and 4. It does not work for an arryay of 8 numbers (1,2,3,4,5,6,7,8). I see that the combination 1 2 3 4 5 6 7 8 gets repeated couple of times. Also there are other combinations that gets repeated. I see that certain combinations don't get displayed even. So could someone tell me what is wrong in the program below. Code: include<stdio.h> int len,numperm=1,count=0; display(int a[]){ int i; for(i=0;i<len;i++) printf("%d ",a[i]); printf("\n"); count++; } swap(int *a,int *b){ int temp; temp=*a; *a=*b; *b=temp; } no_of_perm(){ int x; for(x=1;x<=len;x++) numperm=numperm*x; } perm(int a[]){ int x,y; while(count < numperm){ for(x=0;x<len-1;x++){ swap(&a[x],&a[x+1]); display(a); } swap(&a[0],&a[1]); display(a); for(y=len-1;y>0;y--){ swap(&a[y],&a[y-1]); display(a); } swap(&a[len-1],&a[len-2]); display(a); } } main(int argc, char *argv[]){ if(argc<2){ printf("Error\n"); exit(0); } int i,*a=malloc(sizeof(int)*atoi(argv[1])); len=atoi(argv[1]); for(i=0;i<len;i++) a[i]=i+1; no_of_perm(); perm(a); }

    Read the article

  • assigning a string to another string

    - by user1509676
    Why this code is not running? Why str1 is not assigned to str2 ?? I know i have an option of using strcpy but i wish to know the reason why this is not working?? #include<stdio.h> int main() { char str1[]="hello"; char str2[10]; str2=str1; printf("%s",str2); return 0; } Whereas if I use pointers than it works like here.. #include<stdio.h> int main() ( char *s="good morning"; char *q; q=s; while(*q!='\0') { printf("%c",*q); q++; } return 0; } This works. Now the string has been copied via pointers so why such difference??

    Read the article

  • Strange macro declaration in C

    - by Andrey Atapin
    Exploring libusb-1.0.9 source code, I have found such line (./os/poll_windows.c:78): #define CHECK_INIT_POLLING do {if(!is_polling_set) init_polling();} while(0) As for me this is the same like: #define CHECK_INIT_POLLING if(!is_polling_set) init_polling(); Is there any reason to loop that expression? UPDATE: I couldn't still realize what'd be wrong after the answers, and the following example helped: #include <stdio.h> #define TEST if(test) foo(); #define TEST_DO do { if(test) foo(); } while(0) int test = 1; void foo() { printf("%s", "Foo called"); } int main(int argc, char** argv) { if(argc > 1) TEST_DO; /* LINE 12 */ else printf("%s", "skipping..."); return 0; } If you put TEST at line 12, a compiler will give an error "error: ‘else’ without a previous ‘if’". Hope, this will help someone.

    Read the article

  • C Struct as an argument

    - by Brian
    I'm wondering what's the difference between sample1 and sample2. Why sometimes I have to pass the struct as an argument and sometimes I can do it without passing it in the function? and how would it be if samplex function needs several structs to work with? would you pass several structs as an argument? struct x { int a; int b; char *c; }; void sample1(struct x **z;){ printf(" first member is %d \n", z[0]->a); } void sample2(){ struct x **z; printf(" first member is %d \n", z[0]->a); // seg fault } int main(void) { struct x **z; sample1(z); sample2(); return 0; }

    Read the article

  • How to do hex8 encoding in c?

    - by Tech163
    I am trying to encode a string in hex8 using c. The script I have right now is: int hex8 (char str) { str = printf("%x", str); if(strlen(str) == 1) { return printf("%s", "0", str); } else { return str; } } In this function, I will need to add a 0 ahead of the string if the length is less than 1. I don't know why I'm getting: passing argument 1 of 'strlen' makes pointer from integer without a cast Does anyone know why?

    Read the article

  • CUDA memory transfer issue

    - by Vaibhav Sundriyal
    I am trying to execute a code which first transfers data from CPU to GPU memory and vice-versa. In spite of increasing the volume of data, the data transfer time remains the same as if no data transfer is actually taking place. I am posting the code. #include <stdio.h> /* Core input/output operations */ #include <stdlib.h> /* Conversions, random numbers, memory allocation, etc. */ #include <math.h> /* Common mathematical functions */ #include <time.h> /* Converting between various date/time formats */ #include <cuda.h> /* CUDA related stuff */ #include <sys/time.h> __global__ void device_volume(float *x_d,float *y_d) { int index = blockIdx.x * blockDim.x + threadIdx.x; } int main(void) { float *x_h,*y_h,*x_d,*y_d,*z_h,*z_d; long long size=9999999; long long nbytes=size*sizeof(float); timeval t1,t2; double et; x_h=(float*)malloc(nbytes); y_h=(float*)malloc(nbytes); z_h=(float*)malloc(nbytes); cudaMalloc((void **)&x_d,size*sizeof(float)); cudaMalloc((void **)&y_d,size*sizeof(float)); cudaMalloc((void **)&z_d,size*sizeof(float)); gettimeofday(&t1,NULL); cudaMemcpy(x_d, x_h, nbytes, cudaMemcpyHostToDevice); cudaMemcpy(y_d, y_h, nbytes, cudaMemcpyHostToDevice); cudaMemcpy(z_d, z_h, nbytes, cudaMemcpyHostToDevice); gettimeofday(&t2,NULL); et = (t2.tv_sec - t1.tv_sec) * 1000.0; // sec to ms et += (t2.tv_usec - t1.tv_usec) / 1000.0; // us to ms printf("\n %ld\t\t%f\t\t",nbytes,et); et=0.0; //printf("%f %d\n",seconds,CLOCKS_PER_SEC); // launch a kernel with a single thread to greet from the device //device_volume<<<1,1>>>(x_d,y_d); gettimeofday(&t1,NULL); cudaMemcpy(x_h, x_d, nbytes, cudaMemcpyDeviceToHost); cudaMemcpy(y_h, y_d, nbytes, cudaMemcpyDeviceToHost); cudaMemcpy(z_h, z_d, nbytes, cudaMemcpyDeviceToHost); gettimeofday(&t2,NULL); et = (t2.tv_sec - t1.tv_sec) * 1000.0; // sec to ms et += (t2.tv_usec - t1.tv_usec) / 1000.0; // us to ms printf("%f\n",et); cudaFree(x_d); cudaFree(y_d); cudaFree(z_d); return 0; } Can anybody help me with this issue? Thanks

    Read the article

  • Is there any difference these two pieces of code?

    - by Poiuyt
    #include<stdio.h> class A {public: int a; }; class B: public A {private: int a;}; int main(){ B b; printf("%d", b.a); return 0; } #include<stdio.h> class A {public: int a; }; class B: private A {}; int main(){ B b; printf("%d", b.a); return 0; } I ask because I get different errors: error: 'int B::a' is private error: 'int A::a' is inaccessible Apart from what the errors might reveal, is there any difference at all in the behaviour of these two pieces of code?

    Read the article

  • casting a node to integer

    - by user1708762
    The code gives an error saying that "no operator matches these two operands" in the if comparison statement. I interpret,it should mean that "a node can't be converted/casted into an integer". But, the print statement prints an integer value for w[2] when used with %d format. Why is that happening? Isn't printf casting it? NODE *w=(NODE *)malloc(4*sizeof(NODE)); if(w[2]==0) printf("%d\n",w[2]); The structure of the node is- struct node{ int key; struct node *father; struct node *child[S]; int *ss; int current; };

    Read the article

  • Reading line by line from a file in C

    - by mh234
    What I am trying to do is print out the contents of a file line by line. I run the program in terminal by doing: ./test testText.txt. When I do this, random characters are printed out but not what is in the file. The text file is located in the same folder as the makefile. What's wrong? #include <stdio.h> FILE *fp; int main(int argc, char *argv[]) { char line[15]; fp = fopen(*argv, "r"); while((fgets(line, 15, fp)) != NULL) { printf(line); printf("\n"); } }

    Read the article

  • Obtaining frame pointer in C

    - by assketchum
    I'm trying to get the FP in my C program, I tried two different ways, but they both differ from what I get when I run GDB. The first way I tried, I made a protocol function in C for the Assembly function: int* getEbp(); and my code looks like this: int* ebp = getEbp(); printf("ebp: %08x\n", ebp); // value i get here is 0xbfe2db58 while( esp <= ebp ) esp -= 4; printf( "ebp: %08x, esp" ); //value i get here is 0xbfe2daec My assembly code getEbp: movl %ebp, %eax ret I tried making the prototype function to just return an int, but that also doesn't match up with my GDB output. We are using x86 assembly. EDIT: typos, and my getEsp function looks exactly like the other one: getEsp: movl %esp, %eax ret

    Read the article

  • UITable View Issue,

    - by abc
    hello i am having same issue, i tried your solution but it didnt help me in my case.. i am not getting exception but view is not getting changed.. my piece of code is as below printf("hi"); //Get the selected country NSString *selectedCountry = [listOfItems objectAtIndex:indexPath.row]; //Initialize the detail view controller and display it. DetailViewController *aSecondView = [[DetailViewController alloc] initWithNibName:@"DetailView" bundle:nil]; // aSecondView.selectedCountry = selectedCountry; [self.navigationController pushViewController:aSecondView]; [aSecondView release]; aSecondView = nil; printf("bye.."); both hi and bye gets printed but view doesnt change.. i have wasted 2 days around it .. plz help me out..

    Read the article

  • How to copy the memeory allocated in device function back to main memory

    - by xhe8
    I have a CUDA program containing a host function and a device function Execute(). In the host function, I allocate a global memory output which will then be passed to the device function and used to store the address of the global memory allocated within the device function. I want to access the in-kernel allocated memory in the host function. The following is the code: #include <stdio.h> typedef struct { int * p; int num; } Structure_A; \__global__ void Execute(Structure_A *output); int main(){ Structure_A *output; cudaMalloc((void***)&output,sizeof(Structure_A)*1); dim3 dimBlockExecute(1,1); dim3 dimGridExecute(1,1); Execute<<<dimGridExecute,dimBlockExecute>>>(output); Structure_A * output_cpu; int * p_cpu; cudaError_t err; output_cpu= (Structure_A*)malloc(1); err=cudaMemcpy(output_cpu,output,sizeof(Structure_A),cudaMemcpyDeviceToHost); if( err != cudaSuccess) { printf("CUDA error a: %s\n", cudaGetErrorString(err)); exit(-1); } p_cpu=(int *)malloc(1); err=cudaMemcpy(p_cpu,output_cpu[0].p,sizeof(int),cudaMemcpyDeviceToHost); if( err != cudaSuccess) { printf("CUDA error b: %s\n", cudaGetErrorString(err)); exit(-1); } printf("output=(%d,%d)\n",output_cpu[0].num,p_cpu[0]); return 0; } \__global__ void Execute(Structure_A *output){ int thid=threadIdx.x; output[thid].p= (int*)malloc(thid+1); output[thid].num=(thid+1); output[thid].p[0]=5; } I can compile the program. But when I run it, I got a error showing that there is a invalid argument in the following memory copy function. "err=cudaMemcpy(p_cpu,output_cpu[0].p,sizeof(int),cudaMemcpyDeviceToHost);" CUDA version is 4.2. CUDA card: Tesla C2075 OS: x86_64 GNU/Linux

    Read the article

  • sorting set of five string in alphabetical oder throwing warning?

    - by rost rost
    sorting set of five string in alphabetical oder throwing warning ?my code is below please help me to fix it #include<stdio.h> #include<string.h> int main() { char a[5][20],t[20]; int i,j; printf("enter 5 string\n") scanf("%s",a); for(i=1;i<5;i++) { for(j=1;j<5;j++) { if(strcmp(a[j-1],a[j])>0) { strcpy (t,a[j-1]); strcpy (a[j-1],a[j]); strcpy(a[j],t); } } } for(i=1;i<5;i++) printf("%s\n",a[i]); } ~

    Read the article

  • read after lseek always return 0

    - by Wins
    I'm having an issue reading byte in file after performing lseek long cur_position = lseek(fd, length * -1, SEEK_CUR ); // Rewind file reading by length bytes. printf("cur_position: %i\n", cur_position); int num_byte = read(fd, &byte, 1); printf("num_byte = %i\n", num_byte); With the initial variable length set to 34, the above code would produce cur_position 5 (so there are definitely at least 34 bytes after the lseek function returns), but the variable num_byte returned from function read always returns 0 even though there are still more bytes to read. Does anyone know the reason num_byte always return 0 or do I make mistake in the above code? Just for information, the above code was run on the following machine $ uname -srvpio Linux 3.2.0-24-generic #39-Ubuntu SMP Mon May 21 16:52:17 UTC 2012 x86_64 x86_64 GNU/Linux

    Read the article

  • Assigning variables to pointers

    - by tys
    When compiling the below, the program seem to crash. However, there is no error in the compiling process. ... int *x; *x = 3; printf("%d", *x); ... From what I know, this program initializes the pointer *x to an integer value, and subsequently assigns the value of 3 to the deferenced pointer *x. So why does the program crashes? If I do this instead, the program can work normally. ... int *x, y; y = 3; x = &y; printf("%d", *x); ... So, what seems to be the problem with the skipping of the y variable, and instead, assigning the pointer *x directly to an integer value?

    Read the article

< Previous Page | 30 31 32 33 34 35 36 37 38 39 40 41  | Next Page >