Detailed explanation of the interception function of QString and std::string in Qt

Summary

Abstract: This article will introduce the related functions of using QString and std::string to intercept in Qt. We will detail various commonly used interception functions and how to use them to help you be more flexible and efficient in string processing.

text:

QString interception function

(1) left(n): Intercept the first n characters of the string.

QString str = "Hello, World!";
QString result = str.left(5);  // 结果为"Hello"

(2) right(n): Intercept the last n characters of the string.

QString str = "Hello, World!";
QString result = str.right(6);  // 结果为"World!"

(3) mid(pos, n): Intercept n characters of the string starting from position pos.

QString str = "Hello, World!";
QString result = str.mid(7, 5);  // 结果为 "World"

(4) chopped(n): Remove n characters at the end of the string.

QString str = "Hello, World!";
QString result = str.chopped(7);  // 结果为 "Hello"

(5) section(sep, start, end): Use sep as the separator, and intercept the substring from the start position to the end position.

```cpp
QString str = "apple,orange,banana";
QString result = str.section(',', 1, 1);  // 结果为"orange"

std::string interception function

(1) substr(pos, n): Intercept n characters of the string starting from position pos.

std::string str = "Hello, World!";
std::string result = str.substr(7, 5);  // 结果为 "World"

(2) erase(pos, n): Delete n characters of the string starting from position pos.

std::string str = "Hello, World!";
str.erase(0, 7);  // 结果为"World!"

(3) replace(pos, n, new_str): Replace the n characters of the string from position pos with new_str.

std::string str = "Hello, World!";
str.replace(0, 5, "Hi");  // 结果为 "Hi, World!"

(4) find(sub_str): Find the first position of the substring sub_str in the string.

std::string str = "Hello, World!";
size_t pos = str.find("World");  // 结果为 7

(5) rfind(sub_str): Find the last position of the substring sub_str in the string.

std::string str = "Hello, World!";
size_t pos = str.rfind("o");  // 结果为 7

Summarize:

This article introduces the related functions of using QString and std::string to intercept in Qt. You can use these functions to easily intercept substrings of strings, making string processing more flexible and efficient. I hope the content of this article can help you with string processing in Qt development.