multi-process-non-nested.c

#include <unistd.h>
#include <stdarg.h>
#include <time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>

pid_t create_process(void(*ptr) ());

int tprintf(const char* fmt, ...);
void childProcess();
void parentProcess(pid_t pid);

int main(void){
    int i = 0, j = 0;

    // 父进程输出信息
    printf("Hello from Parent Process, PID is %d.\n", getpid());

    // 创建第一个子进程
    pid_t pid_1 = create_process(childProcess);

    if (pid_1 != -1 && pid_1 != 0){
        // 父进程执行
        parentProcess(pid_1);

        // 创建第二个进程
        pid_t pid_2 = create_process(childProcess);
        
        if (pid_2 = -1 && pid_2 != 0){
            parentProcess(pid_2);
        }else if(pid_2 != 0){
            tprintf("Everything was gone without error.\n");
        }
        // 等待子进程执行完毕
        waitpid(pid_1, NULL, 0);
        waitpid(pid_2, NULL, 0);
    }
    else if(pid_1 != 0){
        tprintf("Everything was gone without error.\n");
    }

    return 0;
}

// 创建进程函数
pid_t create_process(void(*ptr) ()){
    // 创建新进程
    pid_t pid;
    pid = fork();

    if(pid == 0){
        // 该进程执行
        (*ptr)();   // 调用传入的函数
    }
    return pid;
}

// 子进程执行函数
void childProcess(){
    int i;
    sleep(1);
    for (i=0; i<5; ++i){
        printf("Hello from Child Process %d. %d times\n", getpid(), i+1);
        sleep(1);
    }
}

// 父进程执行函数
void parentProcess(pid_t pid){
    // 传入子进程 id，输出进程信息。
    tprintf("Parent forked one child process -- %d.\n", pid);
    tprintf("Parent is waiting for children to exit.\n");
    tprintf("Child process has exited.\n");
    tprintf("Parent had exited.\n");
}

int tprintf(const char* fmt, ...){
    va_list args;
    struct tm * tstruct;
    time_t tsec;
    tstruct = localtime (&tsec);
    printf("%02d:%02d:%02d: %5d|", tstruct->tm_hour, tstruct->tm_min, tstruct->tm_sec, getpid());
    va_start(args, fmt);
    return vprintf(fmt, args);
}