IO作业day4

xmind

作业：创建子父进程，子进程将1.txt内容拷贝到2.txt中，父进程将3.txt内容拷贝到4.txt中。 

#include <myhead.h>
int main(int argc, const char *argv[])
{pid_t pid = fork();if(pid == 0){int fp1 = open("./2.txt",O_WRONLY|O_CREAT|O_TRUNC,0644);if(fp1 == -1){perror("open fp1");return -1;}int fp2 = open("./1.txt",O_RDONLY);if(fp2 == -1){perror("open fp2");return -1;}char s[100];while(1){int p = read(fp2,s,sizeof(s));if(p==0){break;}write(fp1,s,p);}close(fp1);close(fp2);}else if(pid > 0){int fp3 = open("./4.txt",O_WRONLY|O_CREAT|O_TRUNC,0644);if(fp3 == -1){perror("open fp3");return -1;}int fp4 = open("./3.txt",O_RDONLY);if(fp4 == -1){perror("open fp4");return -1;}char a[100];while(1){int p = read(fp4,a,sizeof(a));if(p==0){break;}write(fp3,a,p);}close(fp3);close(fp4);}else{perror("fork");return -1;}return 0;
}