c - 在C中创建自己的toUpper和toLower

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当我运行并编译代码时，出现A和Z以及a和c都未定义的错误，我该如何解决？

char toUpper ( char c ) {

    if ( C >= a + c <= z)
        -32;
    return c;

} // ends toUpper

char toLower ( char c ) {

    if ( c >= A + c <= Z )
        +32;

} // ends toUpper

最佳答案

用单引号将字母引起来以形成字符文字，如下所示：

'a'

关于c - 在C中创建自己的toUpper和toLower ，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/15235998/