Mastering C++ Conversions: A Comprehensive Guide

Unlocking the Power of C++: String to Int Conversion

When working with C++ programming, converting between data types is an essential skill to master. One of the most common conversions is from string to integer. Fortunately, C++ provides several ways to achieve this, making it easy to incorporate into your coding workflow.

The Simplest Approach: Using std::stoi()

Introduced in C++11, the std::stoi() function is the easiest way to convert a string to an integer. This function takes a string as input and returns an integer value. Let’s take a look at an example:

Example 1: C++ String to Int Using std::stoi()

“`

include

include

int main() {
std::string str = “123”;
int num = std::stoi(str);
std::cout << “The integer value is: ” << num << std::endl;
return 0;
}
“`

Output: The integer value is: 123

An Alternative Method: Using std::atoi()

For those who prefer working with character arrays, the std::atoi() function provides a reliable way to convert a char array to an integer. This function is defined in the cstdlib header file.

Example 2: Char Array to Int Using std::atoi()

“`

include

include

int main() {
char str[] = “123”;
int num = std::atoi(str);
std::cout << “The integer value is: ” << num << std::endl;
return 0;
}
“`

Output: The integer value is: 123

The Flip Side: C++ Int to String Conversion

Now that we’ve covered converting strings to integers, let’s explore the reverse process. C++ provides two convenient ways to convert an integer to a string.

The Modern Approach: Using std::to_string()

In C++11, the std::to_string() function was introduced, making it easy to convert an integer to a string.

Example 3: C++ Int to String Using std::to_string()

“`

include

include

int main() {
int num = 123;
std::string str = std::to_string(num);
std::cout << “The string value is: ” << str << std::endl;
return 0;
}
“`

Output: The string value is: 123

The Traditional Method: Using std::stringstream

For older versions of C++, the std::stringstream object provides a reliable way to convert an integer to a string.

Example 4: C++ Int to String Using stringstream

“`

include

include

int main() {
int num = 123;
std::stringstream ss;
ss << num;
std::string str = ss.str();
std::cout << “The string value is: ” << str << std::endl;
return 0;
}
“`

Output: The string value is: 123

Explore More C++ Conversion Options

Want to learn more about converting strings to floats or doubles? Check out our guide on C++ String to float/double.