string-----------
基本输出-------------
read---------
#########while语句的省略写法,
管道和fork-----------
gettimeofday-------
#include <string>
#include <iostream>
using std::string;
int main(){
string aa="hao";
std::cout<<aa;
return 0;
}
基本输出-------------
#include <stdio.h>
main()
{
int c;
while ((c = getchar()) != EOF)
putchar(c);
}
read---------
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#define BUFFSIZE 4096
int
main(void)
{
int n;
char buf[BUFFSIZE];
while ((n = read(STDIN_FILENO, buf, BUFFSIZE)) > 0)
if (write(STDOUT_FILENO, buf, n) != n)
printf("write error");
if (n < 0)
printf("read error");
exit(0);
}
#########while语句的省略写法,
管道和fork-----------
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#define MAXLINE 4096
int
main(void)
{
int n;
int fd[2];
pid_t pid;
char line[MAXLINE];
if (pipe(fd) < 0)
printf("pipe error");
if ((pid = fork()) < 0) {
printf("fork error");
} else if (pid > 0) { /* parent */
close(fd[0]);
write(fd[1], "hello world\n", 12);
} else { /* child */
close(fd[1]);
n = read(fd[0], line, MAXLINE);
write(STDOUT_FILENO, line, n);
}
exit(0);
}
gettimeofday-------
#include <stdio.h>
#include <sys/time.h>
#include <time.h>
int main(int argc, char * argv[]){
struct timeval tv; //(1)
while(1){
gettimeofday(&tv, NULL); //(2)
printf("time %u:%u\n", tv.tv_sec, tv.tv_usec);
sleep(2);
}
return 0;
}