How does the C++ function library perform string operations?

The C standard library provides a rich library of string operation functions, including obtaining C-style strings (std::string::c_str()), obtaining string length (std::string::size()), Basic operations such as checking whether a string is empty (std::string::empty()) and finding substrings (std::string::find()). In addition, there are operations for modifying strings (append, replace, delete) and comparing strings (equality, inclusion). This practical example shows how to read text from the user and convert it to uppercase.

String operations in the C function library

The C standard library provides a rich function library to process strings, allowing Developers can easily perform various string operations.

Basic operations

• ##std::string::c_str(): Convert string to C-style null character Ending character array.
• std::string::size(): Returns the number of characters in the string.
• std::string::empty(): Check whether the string is empty.
• std::string::find(): Find a substring in a string.

String modification

• std::string::append(): Append another string to The current string.
• std::string::replace(): Replace the substring in the current string with a new string.
• std::string::erase(): Remove a substring or character from the current string.
• std::string::operator and operator =: Concatenate two strings.

String comparison

• std::string::compare(): Compare two strings.
• std::string::operator== and operator!=: Check whether two strings are equal or not equal.
• std::string::find_first_of(): Find a specific character or set of characters in a string.

Practical Case

Let us create a program that reads a line of text from the user and converts it to uppercase.

#include <iostream>
#include <string>

using namespace std;

int main() {
    // 从用户读取一行文本
    cout << "输入一行文本：" << endl;
    string text;
    getline(cin, text);

    // 将文本转换为大写
    for (size_t i = 0; i < text.size(); i++) {
        text[i] = toupper(text[i]);
    }

    // 输出转换后的文本
    cout << "转换后的文本：" << text << endl;

    return 0;
}

Output:

输入一行文本：
Hello World!

转换后的文本：
HELLO WORLD!

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