c如何将字符变量与字符串进行比较? [英] How does c compare character variable against string?

问题描述

以下代码在 C 中完全可以，但在 C++ 中则不行.在以下代码中，if 语句始终为 false.C如何比较字符变量和字符串?

The following code is completely ok in C but not in C++. In following code if statement is always false. How C compares character variable against string?

int main()
{
  char ch='a';
  if(ch=="a")
    printf("confusion");
  return 0;
}

推荐答案

以下代码在C中完全没问题

不，完全没有.

在您的代码中

  if(ch=="a")

本质上是试图将 ch 的值与字符串文字 "a" 的基地址进行比较.这是无意义和无用的.

is essentially trying to compare the value of ch with the base address of the string literal "a",. This is meaning-and-use-less.

这里你想要的是使用单引号(')来表示一个char字面量，比如

What you want here, is to use single quotes (') to denote a char literal, like

  if(ch == 'a')

<小时>

注意 1:

详细说明char字面量的单引号和字符串字面量的双引号的区别，

To elaborate on the difference between single quotes for char literals and double quotes for string literal s,

对于 char 文字，C11，章节 §6.4.4.4

For char literal, C11, chapter §6.4.4.4

整数字符常量是一个或多个用单引号括起来的多字节字符的序列，如 'x'

An integer character constant is a sequence of one or more multibyte characters enclosed in single-quotes, as in 'x'

对于字符串字面量，第 6.4.5 章

and, for string literal, chapter §6.4.5

字符串字面量是包含在双引号，如 "xyz".

Acharacter string literal is a sequence of zero or more multibyte characters enclosed in double-quotes, as in "xyz".

<小时>

注意 2:

也就是说，作为注释，main() 的推荐签名是 int main(void).

That said, as a note, the recommend signature of main() is int main(void).

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