从 C 语言中的给定字符串中删除前面的空格和制表符 [英] Remove preceding spaces and tabs from a given string in C language

问题描述

什么 C 函数(如果有)从字符串中删除所有前面的空格和制表符?

What C function, if any, removes all preceding spaces and tabs from a string?

推荐答案

在 C 中，字符串由指针标识，例如 char *str，也可能是数组.无论哪种方式，我们都可以声明我们自己的指向字符串开头的指针:

In C a string is identified by a pointer, such as char *str, or possibly an array. Either way, we can declare our own pointer that will point to the start of the string:

char *c = str;

然后我们可以让我们的指针越过任何类似空格的字符:

Then we can make our pointer move past any space-like characters:

while (isspace(*c))
    ++c;

这将使指针向前移动，直到它不指向空格，即在任何前导空格或制表符之后.这使原始字符串保持不变 - 我们刚刚更改了指针 c 指向的位置.

That will move the pointer forwards until it is not pointing to a space, i.e. after any leading spaces or tabs. This leaves the original string unmodified - we've just changed the location our pointer c is pointing at.

你需要这个包含来获取 isspace:

You will need this include to get isspace:

#include <ctype.h>

或者，如果您愿意自己定义什么是空白字符，您可以编写一个表达式:

Or if you are happy to define your own idea of what is a whitespace character, you can just write an expression:

while ((*c == ' ') || (*c == '	'))
    ++c;

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