主要的問題：
1 pipe返回的壹對描述符，如果自己只用了寫，那麽把讀關掉，而不是都關掉。
2 strtok的用法不對
3 打印信息有誤導，send和receive沒有列寫清楚。
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <time.h>
int main(int argc,char *argv[])
{
pid_t childpid;
int error;
int fd[2];
int i;
int nprocs;
long num1,num2;
char mybuf[512]={0};
char *bp = mybuf;
int a,b,c;
int n;
if((argc!=2)||((nprocs=atoi(argv[1]))<=0)){
fprintf(stderr,"Usage:%s nprocs\n",argv[0]);
return 1;
}
if(pipe(fd) == -1){
perror("Failed to create starting pipe");
return 1;
}
if((dup2(fd[0],STDIN_FILENO) == -1) || (dup2(fd[1],STDOUT_FILENO) == -1)){
perror("Failed to conect pipe");
return 1;
}
for(i=1;i<nprocs;i++){
if(pipe(fd) == -1){
fprintf(stderr,"[%ld]:failed to create pipe %d: %s\n",(long)getpid(),i,strerror(errno));
return 1;
}
if((childpid = fork()) == -1){
fprintf(stderr,"[%ld]:failed to creat a child %d: %s\n",(long)getpid(),i,strerror(errno));
return 1;
}
if(childpid>0) {
error=dup2(fd[1],STDOUT_FILENO);
close(fd[0]);
}
else {
error=dup2(fd[0],STDIN_FILENO);
close(fd[1]);
}
if(error == -1){
fprintf(stderr,"[%ld]:failed to dup pipes for iteration %d %s\n",(long)getpid(),i,strerror(errno));
return 1;
}
if(childpid)
break;
}
if(i == 1)
{
a = 1;
b = 1;
sprintf(mybuf,"%d:%d",a,b);
write(STDOUT_FILENO,mybuf,strlen(mybuf)+1);
fprintf(stderr,"This is id:%d with pid:%d parent pid:%d send:%s\n",
i,getpid(),getppid(),mybuf);
read(STDIN_FILENO,mybuf,32);
fprintf(stderr,"This is id:%d with pid:%d parent pid:%d received:%s\n",
i,getpid(),getppid(),mybuf);
}
else if(read(STDIN_FILENO,mybuf,32) != -1)
{
fprintf(stderr,"This is id:%d with pid:%d parent pid:%d received:%s\n",
i,getpid(),getppid(),mybuf);
a = atoi(strtok(mybuf, ":"));
b = atoi(strtok(NULL, ":"));
c = a + b;
fprintf(stderr,"This is id:%d with pid:%d key:%d:%d\n",i,getpid(), a, b);
sprintf(mybuf,"%d:%d",b,c);
write(STDOUT_FILENO,mybuf,strlen(mybuf)+1);
fprintf(stderr,"This is id:%d with pid:%d parent pid:%d send:%s\n",
i,getpid(),getppid(),mybuf);
}
wait(NULL);
return 0;
}