C: 如何比较两个字符串? [英] C: How to compare two strings?

问题描述

这是重复的，我已将其标记为这样.请参阅[问题] 为什么是a"!= 一个"在 C 中?

This is a duplicate and I've flagged it as such. See [question] Why is "a" != "a" in C?

所以我试图根据结构中的字段打印出特定的消息.该字段包含字符串1".

So I'm trying to print out a specific message depending on a field within a struct. The field contains the string "1".

每当我运行 printf("%s", record.fields[2]); 时，输出都是 1;我没有格式警告.

Whenever I run printf("%s", record.fields[2]); the output is 1; I've no format warnings.

但是，当我根据相应的字符串(在本例中为1")检查该字段时，检查失败:

However, when I check the field against the corresponding string (in this case, "1"), it fails the check:

if (record.fields[2] == "1") {
    printf("The field is 1!");
}

推荐答案

你需要使用strncmp 比较字符串:

You need to use strncmp to compare strings:

if (strncmp(record.fields[2], "1", 1) == 0) ...

您需要与零进行比较，因为当两个字符串相同时，strcmp 返回零.

You need to compare to zero, because strcmp returns zero when two strings are identical.

但是，您似乎不是在比较字符串:而是在字符串中查找特定字符.在这种情况下，您需要使用字符常量而不是字符串文字(带单引号):

However, it looks like you are not comparing strings: rather, you are looking for a specific character inside the string. In this case, you need to use a character constant instead of a string literal (with single quotes):

if (record.fields[2] == '1') ...

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