C/C++之cctype字符处理

本文主要是介绍C/C++之cctype字符处理，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

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#include <cctype>	// #include <ctype.h>

检查

函数	重点	功能
isalnum	字母、数字	Check if character is alphanumeric (function )
isdigit	数字	Check if character is decimal digit (function )
isalpha	字母	Check if character is alphabetic (function )
islower	小写字母	Check if character is lowercase letter (function )
isupper	大写字母	Check if character is uppercase letter (function )
isblank		Check if character is blank (function )
iscntrl		Check if character is a control character (function )
isgraph		Check if character has graphical representation (function )
isprint		Check if character is printable (function )
ispunct		Check if character is a punctuation character (function )
isspace		Check if character is a white-space (function )
isxdigit		Check if character is hexadecimal digit (function )

string s = "AB34cd.?";
for(char ch:s)
{cout << isalnum(ch) << " ";
}
// 1 4 2 0 0 

转化

函数	重点	功能
tolower	大写变小写	Convert uppercase letter to lowercase (function )
toupper	小写变大写	Convert lowercase letter to uppercase (function )

string s = "AB34cd.?";
for (int i = 0; i < s.size(); i++)
{s[i] = tolower(s[i]);
}
cout << s << endl; //ab34cd.?

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