C Snippets

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
 
int main(int argc, char *argv[])
{
    if (argc != 3){
        printf("Usage: %s dir1/fileA dir2/fileB\n", argv[0]);
        exit(1);
    }
 
    FILE *fp1, *fp2;
 
    char *file1 = argv[1];
    char *file2 = argv[2];
    char *error_str = "Open file ";
 
    if (NULL == (fp1 = fopen(file1, "r"))){
        sprintf(error_str, "Error open file %s\n", file1);
        perror(error_str);
        exit(1);
    }
 
    if (NULL == (fp2 = fopen(file2, "w"))){
        sprintf(error_str, "Error open file %s\n", file2);
        perror(error_str);
        exit(1);
    }
 
    int ch;
    while ((ch = fgetc(fp1)) != EOF){
        fputc(ch, fp2);
    }
 
    fclose(fp1);
    fclose(fp2);
    
    return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
 
#define NLOOP 5000
 
int counter;
pthread_mutex_t counter_mutex = PTHREAD_MUTEX_INITIALIZER;
 
void *doit(void *);
 
int main(int argc, char **argv)
{
    pthread_t tidA, tidB;
 
    pthread_create(&tidA, NULL, doit, NULL);
    pthread_create(&tidB, NULL, doit, NULL);
 
    /* wait for both threads to terminate */
    pthread_join(tidA, NULL);
    pthread_join(tidB, NULL);
 
    return 0;
}
 
void *doit(void *vptr)
{
    int i, val;
 
    /* Each thread fetches, prints, and increments the counter NLOOP times.
     * The value of the counter should increase monotonically.
     */
 
    for (i = 0; i < NLOOP; i++){
        pthread_mutex_lock(&counter_mutex);
 
        val = counter;
        printf("%x: %d\n", (unsigned int)pthread_self(), val + 1);
        counter = val + 1;
 
        pthread_mutex_unlock(&counter_mutex);
    }
 
    return NULL;
}

// 返回自系统开机以来的毫秒数（tick）
unsigned long GetTickCount()
{
    struct timespec ts;
    clock_gettime(CLOCK_MONOTONIC, &ts);
    return (ts.tv_sec * 1000 + ts.tv_nsec / 1000000);
}