#include <iostream>
int main()
{
    std::string str("   字符串   String    ");
    std::cout << str << std::endl;
    std::cout << str.size() << std::endl;
    str.erase(str.find_first_of(' '), str.find_first_not_of(' '));
    str.erase(str.find_last_not_of(' ') + 1);
    std::cout << str << std::endl;
    std::cout << str.size() << std::endl;
    return 0;
}

#include <stdio.h>
#include <string.h>
#define STRING_LENGTH 10000
int main()
{
    const char *text = "   字符串   String    ";
    printf("%s\n%u\n", text, strlen(text));
    while (*text == ' ')
        ++text;
    char str[STRING_LENGTH];
    strcpy(str, text);
    size_t i = strlen(str) - 1;
    while (str[i] == ' ')
        str[i--] = '\0';
    printf("%s\n%u\n", str, strlen(str));
    return 0;
}

g++ -std=c++11 StdStringTrimTest.cpp -o StdStringTrimTest
gcc -std=c11 CStyleStringTrimTest.c -o CStyleStringTrimTest