如何大写和标题字符串

Question

如果给我一个字符串，我需要大写或标题字符串。例如：

Answer 1

您的代码存在一些问题。以下是您的代码的修改版本，工作正常。这里：

std::string Capitalize(const std::string &str) {
std::string Ret;
for (int i = 0; i < str.length(); i++){
    char c = str[i];
    if (i == 0){
        Ret += toupper(c);
    }
    else if (i != 0){
        Ret += (tolower(c));
    }
}
return Ret;}

for循环中的条件需要是str.length（）而不是Ret.length（），这里：

std::string Title(const std::string &str) {
std::string Ret;
int i=0;
for (int i=0;i<str.size();i++) {
    if(!(i==0 && str[i]==' '))
        Ret += tolower(str[i]);
}

int size = Ret.length();
for (int i = 0; i < size; i++) {
    if (i==0  || Ret[i - 1] == ' ')
    {
        Ret[i] = toupper(Ret[i]);
    }
}
return Ret;}

检查i是否为0以防止超出范围访问字符串。

Answer 2

使用字符串流首先拆分所有单词，以便您可以使用向量轻松完成此操作。这是Title函数的一个实现：

 std::string Title(const std::string &str) {
     std::vector<string>words;
     words.clear();
     std::string res = str, std::ans = "";
     // It's better to pass the string AFTER you convert it all lowercase. Or you can only work with the capitalized characters:
     for(int i = 0; i < res.size(); ++i){
         if(res[i] >= 'A' && res[i] <= 'Z'){
             res[i] = tolower(res[i]);
         }
     }

     istringstream ss(res); // We push the modified string into a stringstream.

     do{
        res = "";
        ss >> res;
        words.push_back(res); // We split the string at " " and push each word in the vector.
     } while(ss)


     for(int i = 0; i < words.size(); ++i){
           res = words[i];
           res[0] = toUpper(res[0]); // For each word, we capitalize it
           ans += res; // We add the word to our return string.
           if(i < words.size() - 1){
               ans += " "; // If this is not the last word, add a space 
           }
     }
     return ans;
 }

至于大写，您可以这样做：

std::string Capitalize(const std::string &&str){

    std::string res = str;
    res[0] = toupper(res[0]);
    for(int i = 1; i < res.size(); ++i){
        if(res[i] >= 'A' && res[i] <= 'Z'){
            res[i] = tolower(res[i]); // converting if only an uppercase character.
        }
    }
    return res; // If you pass a reference, the original will be modified so no return required.
}