eclipse中的关于scanf和printf的输入顺序的解决办法

最新推荐文章于 2021-05-20 00:15:28 发布

iteye_19401

最新推荐文章于 2021-05-20 00:15:28 发布

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分类专栏： c 文章标签：开发工具

本文链接：https://blog.youkuaiyun.com/iteye_19401/article/details/82207630

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本文探讨了在Eclipse环境中运行C程序时遇到的一个奇怪现象：输入和输出操作似乎被成组执行，导致程序行为不符合预期。通过使用fflush(stdout)解决此问题的方法。

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The eclipse console has weird behaviour when used for input with C programs.
I teach C to first year undergraduates and I want them to learn their way through eclipse. But the small silly programs that ask you to input characters have weird behaviour, if you use the eclipse console. It seems like it groups all input and output commands and executes them together...for example...
the following program:

#include <stdio.h>

int main() {
int n = 0;
printf("Gimme a number: ");
scanf ("%d", &n);
printf("/nThe number you entered was %d/n", n);

return 0;
}

has the following output:

4
Gimme a number: The number you entered was 4

Pretty normal output on any console you'll find, not just with eclipse's one

instead of

Gimme a number: 4
The number you entered was 4

To obtain this output, you have to flush stdout before scanf'ing the number. The output is flushed either implicitely when a newline character is echoed on the console (printf("/n")) or explicitely with fflush(stdout);

to get the output you wanted use this program :

#include <stdio.h>

int main() {

    int n = 0;
    printf("Gimme a number: ");
    fflush(stdout);
    scanf ("%d", &n);
    printf("/nThe number you entered was %d/n", n);

return 0;
}