文件IO

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#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;
}

多线程

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#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;
}

便利函数

获取系统运行时间

Windows 下有现成的函数 GetTickCount()

Linux 下 GetTickCount() 的实现:

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// 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);
}