scanf动态分配 [英] scanf dynamic allocation

问题描述

无论什么原因，以下代码打印（null）：

For whatever reason the following code prints (null):

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
    char *foo; 
    scanf("%ms", &foo);
    printf("%s", foo);
    free(foo);
}

我正在动态地为字符串分配内存，但正如我之前所说我的程序只输出（null）。我通过使用getche和realloc做一个函数来解决这个问题，但是似乎几乎没有意义，因为我还必须编程如果用户进入backspace，tab等等会发生什么。但正如我所说的只是一个工作我宁愿知道为什么上面的代码不工作...

I'm trying to allocate memory for a string dynamically but as I said earlier my program simply outputs (null). I worked around this by making a function using getche and realloc but it seems almost pointless due to the fact that I also had to program what would happen if the user entered backspace, tab, etc.. But as I said that is just a work around and I would rather know why the above code is not working...

附加信息：

我我使用Pelles C IDE v7.00并用C11标准编译

I am using the Pelles C IDE v7.00 and compiling with the C11 standard

推荐答案

我没有看到 ％m 在草案C11标准（ fscanf 的部分）。我建议你避免它，并像C99一样调用 malloc（）。

I am not seeing %m in section 7.21.6.2 of the Draft C11 standard (the section on fscanf). I suggest that you avoid it and call malloc() as you would in C99.

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