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replaceString

0 likes • Nov 14, 2021 • 0 views
C
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pipe() example

0 likes • Nov 19, 2022 • 0 views
C
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#define READ 0 /* The index of the read end of the pipe */
#define WRITE 1 /* The index of the write end of the pipe */
char * phrase = "This goes in the pipe";
int main() {
int fd[2], bytesRead;
char message[100]; /* Parent process' message buffer */
pipe(fd); /* Create unnamed pipe */
if (fork() == 0) /* Child, writer */ {
close(fd[READ]); /* Close unused end */
write(fd[WRITE], phrase, strlen(phrase) + 1); /* Include NULL */
close(fd[WRITE]); /* Close used end */
} else /* Parent, reader */ {
close(fd[WRITE]); /* Close unused end */
bytesRead = read(fd[READ], message, 100);
printf("Parent just read %i bytes: %s\n", bytesRead, message);
close(fd[READ]); /* Close used end */
}
}

Bitwise operators with pointers

0 likes • Nov 18, 2022 • 0 views
C
#include <stdio.h>
#include <stdlib.h>
int main(){
int * int_ptr;
int_ptr = (int *)malloc(2*sizeof(int));
if(!int_ptr) {
printf("Something went wrong while allocating memory. Exiting...");
exit(1);
}
printf("Enter first integer: ");
scanf("%i", &int_ptr[0]);
printf("Enter second integer: ");
scanf("%i", &int_ptr[1]);
printf("Original values: 1st = %i 2nd = %i\n",int_ptr[0], int_ptr[1]);
int_ptr[0] = int_ptr[0] ^ int_ptr[1];
//printf("%i\n", int_ptr[0]);
int_ptr[1] = int_ptr[0] ^ int_ptr[1];
//printf("%i\n", int_ptr[1]);
int_ptr[0] = int_ptr[0] ^ int_ptr[1];
//printf("%i\n", int_ptr[0]);
printf("Swapped values: 1st = %i 2nd = %i\n", int_ptr[0], int_ptr[1]);
free(int_ptr);
exit(0);
}

fork() example

0 likes • Nov 19, 2022 • 1 view
C
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
int main() {
pid_t pid; /* could be int */
int i;
pid = fork();
printf("PID=%d\n", pid);
if (pid > 0) {
/* parent */
for (i = 0; i < 10; i++)
printf("\t\t\tPARENT %d\n", i);
} else {
/* child */
for (i = 0; i < 10; i++)
printf("CHILD %d\n", i);
}
return 0;
}

Fast inverse square root

0 likes • Nov 19, 2022 • 0 views
C
// The following code is the fast inverse square root implementation from Quake III Arena
// this code has been stripped of C preprocessor directives, but includes the exact original comment text
float Q_rsqrt( float number )
{
long i;
float x2, y;
const float threehalfs = 1.5F;
x2 = number * 0.5F;
y = number;
i = * ( long * ) &y; // evil floating point bit level hacking
i = 0x5f3759df - ( i >> 1 ); // what the fuck?
y = * ( float * ) &i;
y = y * ( threehalfs - ( x2 * y * y ) ); // 1st iteration
// y = y * ( threehalfs - ( x2 * y * y ) ); // 2nd iteration, this can be removed
return y;
}

execlp() example

0 likes • Nov 19, 2022 • 0 views
C
#include <stdio.h>
#include <unistd.h>
int main() {
char * cmd[] = {
"who",
"ls",
"date"
};
int i;
printf("0=who 1=ls 2=date : ");
scanf("%d", & i);
execlp(cmd[i], cmd[i], (char * ) 0);
printf("execlp failed\n");
return 0;
}

wait() example

0 likes • Nov 19, 2022 • 0 views
C
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
int main() {
char * cmd[] = {
"who",
"ls",
"date"
};
int i;
while (1) {
printf("0=who 1=ls 2=date : ");
scanf("%d", & i);
if (fork() == 0) {
/* child */
execlp(cmd[i], cmd[i], (char * ) 0);
printf("execlp failed\n");
exit(1);
} else {
/* parent */
wait((int * ) 0);
printf("child finished\n");
}
} /* while */
} /* main */