printf 就在延迟之前在 C 中不起作用 [英] printf just before a delay doesn't work in C

问题描述

有谁知道为什么如果我在延迟之前放一个 printf，它会等到延迟完成后才打印消息?

Does anyone know why if i put a printf just before a delay it waits until the delay is finished before it prints de message?

带有 sleep() 的代码 1:

Code1 with sleep():

int main (void)
{
    printf ("hi world");
    system("sleep 3");    
}

具有自我实现延迟的代码 2:

Code2 with a self implemented delay:

void delay(float sec)
{
    time_t start;
    time_t current;
    time(&start);
    do{
        time(&current);
    }while(difftime(current,start) < sec);
}
int main (void)
{
    printf ("hi world");
    delay(3);    
}

如果:

printf ("hi world");
delay(3);    
printf ("hi world");
delay(3);    

它等待睡眠的总和，然后同时打印消息

it waits until the sum of sleeps and then it prints the messages at the same time

为什么会发生这种情况?

Why does this happen?

更新:我在调用延迟时写了延迟(睡眠3")，我的意思是延迟(3).更正

推荐答案

标准输出不会刷新，直到您输出 '\n' 字符.

the standard output is not flush until you output a '\n' char.

试试 printf ("hi world\n");

try printf ("hi world\n");

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