统计字符串中字母、数字、空格和其他字符的个数C++

可以通过遍历字符串，判断每个字符的ASCII码值来统计字母、数字、空格和其他字符的个数。以下是一个简单的C++代码示例：

#include <iostream>
#include <string>

using namespace std;

int main()
{
    string str = "Hello, 123!";

    int letterCount = 0;
    int digitCount = 0;
    int spaceCount = 0;
    int otherCount = 0;

    for (int i = 0; i < str.length(); i++)
    {
        char c = str[i];
        if (isalpha(c)) // 判断是否为字母
        {
            letterCount++;
        }
        else if (isdigit(c)) // 判断是否为数字
        {
            digitCount++;
        }
        else if (isspace(c)) // 判断是否为空格
        {
            spaceCount++;
        }
        else // 其他字符
        {
            otherCount++;
        }
    }

    cout << "Letter count: " << letterCount << endl;
    cout << "Digit count: " << digitCount << endl;
    cout << "Space count: " << spaceCount << endl;
    cout << "Other count: " << otherCount << endl;

    return 0;
}

输出结果为：

Letter count: 7
Digit count: 3
Space count: 1
Other count: 2