我无法正确接受用户的输入 [英] i can't take input from user properly

问题描述

我曾经使用过 scanf()；但是visual studio告诉我这不安全，当我使用 fgets();它只输入前两个输入，第三个被忽略

i used to work with scanf(); but visual studio tells me it's not safe, when i use fgets(); it only inputs the first two input and the third one is ignored

void main() {

    char c=' ';
    char s[20];
    char sen[40];
    fgets(&c, sizeof(c), stdin);
    fgets(s, sizeof(s), stdin);
    fgets(sen, sizeof(sen), stdin);

    system("pause");

}

这里它实现了前两个，第三个 fgets 完全被忽略为什么??以及在 c 中从用户那里获取输入的良好做法是什么?

here it implements the first two and the third fgets is totally ignored WHY?? and what are the good practices in taking input from user in c?

推荐答案

fgets 将在缓冲区内存储空终止符和回车符.所以你应该确保缓冲区足够大来存储你的数据+空终止符+回车.如果你使用像 c 这样的单个字符，那么它应该是一个大小为 3 的数组. Character+0+\n对数组进行零初始化也是一种很好的做法.

fgets will store the null terminator along with the carriage return inside the buffer. SO you should make sure the buffer is large enough to store your data+null terminator+carriage return. If you are taking a single character like c, then it should be an array of size 3. Character+0+\n It's also good practice to zero initialise your arrays.

#include <stdio.h>
int main() {

    char c[3] = {0};
    char s[20] = {0};
    char sen[40] = {0};
    fgets(c, sizeof(c), stdin);
    fgets(s, sizeof(s), stdin);
    fgets(sen, sizeof(sen), stdin);
    return 0;
}

并使用 int main 而不是 void main.

And use int main instead of void main.

如果你确实想在 fgets 中使用单个字符输入，你可以通过阅读自己清除输入流，直到从流中拉回回车.

If you do want to use a single character input in fgets, you can clear the input stream yourself by reading until carriage return is pulled from the stream.

#include <stdio.h>
int main() {

    char c;
    char s[20] = {0};
    char sen[40] = {0};
    fgets(&c, sizeof(c), stdin);

    while(getchar() != '\n'); //read until carriage return

    fgets(s, sizeof(s), stdin);
    fgets(sen, sizeof(sen), stdin);
    return 0;
}

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