C++ string to_string Function

C++ String to_string()

The std::to_string() function in C++ converts numerical values into their string representation. Introduced in C++11 and defined in the <string> header, this function is used to transform various numeric types into std::string objects.

Syntax of string to_string() function

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std::string to_string(int val);
std::string to_string(long val);
std::string to_string(long long val);
std::string to_string(unsigned val);
std::string to_string(unsigned long val);
std::string to_string(unsigned long long val);
std::string to_string(float val);
std::string to_string(double val);
std::string to_string(long double val);

Parameters of string to_string() function

Parameter	Description
`val`	The numerical value to be converted to a string. It can be of any numeric data type such as `int`, `long`, `float`, `double`, etc.

Return Value of string to_string() function

The function returns a std::string object containing the textual representation of the input numerical value.

Exceptions for string to_string() function

The std::to_string() function may throw a std::bad_alloc exception if there is insufficient memory to allocate the resulting string.

Examples for string to_string() function

Example 1: Converting an Integer to String

In this example, we convert an integer value to a string using std::to_string() and concatenate it with another string.

Program

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#include <iostream>
#include <string>

int main() {
    int number = 42;
    std::string result = "The answer is " + std::to_string(number);
    std::cout << result << std::endl;
    return 0;
}

Output

The answer is 42

Explanation

The program includes the necessary headers: <iostream> for input and output operations, and <string> for string handling.
An integer variable number is initialized with the value 42.
The std::to_string() function converts the integer to a string, which is then concatenated with another string to form the final message.
The program outputs the concatenated string using std::cout.

Example 2: Converting a Floating-Point Number to String

This example demonstrates converting a floating-point number to a string and appending additional text.

Program

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#include <iostream>
#include <string>

int main() {
    double pi = 3.141592653589793;
    std::string result = "The value of pi is approximately " + std::to_string(pi);
    std::cout << result << std::endl;
    return 0;
}

Output

The value of pi is approximately 3.141593

Explanation

The program includes the necessary headers: <iostream> for input/output operations and <string> for string handling.
A double variable pi is initialized with the value of π (pi).
The std::to_string() function converts the double to a string. Note that the function may limit the precision of floating-point numbers, typically to six decimal places.
The resulting string is concatenated with additional text and printed using std::cout.

Notes

When converting floating-point numbers, std::to_string() may not preserve the full precision of the value. For higher precision requirements, consider using std::ostringstream with appropriate formatting settings.
The function relies on the current C locale for formatting purposes, which may affect the output in multi-threaded environments.

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C++ string to_string Function