C++ hex string to int

In C++ programming language, one has to deal with different data representations, i.e. binary, hexadecimal, integer, etc. Hexadecimal strings are often used to represent binary-coded data or memory addresses that may need to be converted to integers for various operations. This article explores the process of converting hexadecimal strings to integers in C++, covering the essential concepts, methods, and some examples to help you understand how to convert hexadecimal strings to integers in the C++ programming language. be changed.

Hexadecimal representation in C++

Using the base-16 digit system, commonly called hexadecimal or simply “hex”, is standard practice in computing. In C++, hexadecimal values ​​are usually identified by a preceding “0x”. For example, the hexadecimal number 0x1A is equivalent to the decimal number 26. Hexadecimal string consists of the characters '0' to '9' and 'A' to 'F' (or 'A' to 'F'), where 'A' to 'F' represents values ​​from 10 to 15.

Conversion between hex strings and other numerical forms such as binary, integer, and decimal is possible in C++ using built-in functions such as Stoi(), sscanf(), and Stoul(), all of which facilitate conversion to and from hex strings. For an int. Similarly, StringStream provides a more generalized approach. The following discussion highlights several methods that are used to convert a hex string to its corresponding integer number.

C++ Converting Hex String to Int

C++ provides robust mechanisms for converting hex strings to integers. The conversion process involves parsing each character within the string and calculating its equivalent decimal number. Following are some examples that show how to convert a C++ hex string to an int:

Method 1: stoi() function

The C++ standard library provides the Stoi() function, which is capable of converting numeric strings—binary, octal, or hexadecimal—to unsigned integers within a specified base. to the function Defined in header file. It requires a maximum of three arguments:

String Name: Number string intended for conversion to decimal format.

Serial Number: This alternative index is, by default, 0 and can also be set to nullptr.

Base: Another optional argument indicating the base number system of the supplied string. Its default value is 10, which represents decimal string input.

The stoi() function outputs an integer representation of the provided hex string. Here is the syntax of the Stoi() function:

Syntax:

An example program in C++ that uses the Stoi() function to convert a hexadecimal string to an integer is as follows:

Let's execute this code, check the results and see what we get.

The compiler throws an “invalid argument” error. Let us explain why this happened.

The Stoi() function in C++ is designed to extract and convert an initial integer value from a given string argument. It processes integers from the beginning of the string, stopping when reaching a character that is not an integer or at the end of the string.

A runtime exception occurs when attempting to run the previous program because the Stoi() function stops processing and exits when it encounters non-numeric characters or spaces. If the first character of the string does not correspond to an integer, Stoi() will terminate immediately.

Now, let's give the Stoi() function with another input and see its response.

Following is the output for the given input in stoi() function:

Here, the Stoi() function converts the “1285” part in the given string “1285St” and ignores the “St” part.

Method 2: stool() function

The stall() function provided by the C++ standard library within the header enables conversion from string to integer. Similar to the stoi() function, it also requires three input parameters:

String Name: This digit represents the name of the string that will be converted to an integer.

Index Indicator: A pointer to the size of the input string which is optional and defaults to 0 and can be nullptr if not used.

Base: The input of given base numbers determines their interpretation and valid characters. In this case, it is base 16 because it is a hexadecimal string.

The stall() function outputs the integer representation of the provided hexadecimal string. Here is the syntax of the stall() function:

Syntax:

Here's an example to illustrate how Stoul() can be used in C++ to convert a hexadecimal string to an unsigned integer:

The stall() function of the given program produces the following output:

Method 3: Sscanf() Function

Now, let's learn about the sscanf() function in C++ hex to int conversion. This Is included via header and allows various data conversion types from hex string to integer. For the sscanf() function, the following arguments need to be provided:

input string: The string you want to convert to an integer.

Format String: A format string that outlines the expected format of the source string. Use the “%x” format specifier for hexadecimal to integer conversion.

Indicator: It represents a variable that stores the changed value.

The result of the sscanf() function is also a converted integer representation of the given hex string. Now, let's look at the syntax of the sscanf() function.

Syntax:

The following example demonstrates how the sscanf() function works to convert a C++ hex string to an int. Let us look at the following given example:

As you may have noticed, The header is included in this example but not in the previous example. This is because the sscanf() function Provided by the Library. Another difference you may notice here is that “0x” leads the input string. “0x” is intentionally added to the string to show that the transformation functions work the same with or without “0x” on the given input. The second argument to the sscanf() function is to determine the format of the string. Upon executing this program, the following output is produced:

The execution time required for the sscanf() function is affected by the length of the input and format strings. Additionally, the time taken is affected by the complexity of the functions that are applied during the parsing steps. Typically, sscanf() exhibits a linear time complexity (O(N)) relative to the length of the input string because it processes the string one character at a time, performing one action with each progression. However, the exact time complexity may vary depending on the specific format string and input length.

conclusion

This article took an in-depth look at three different methods for converting hexadecimal strings to integers in C++. By going deeper into the details and providing practical examples, we described the use of the Stoi(), Stoul(), and sscanf() functions, each of which acts as a powerful tool in C++ for hex string to int conversion. Does. These methods cater to different needs and scenarios: Stoi() for signed integers, Stoul() for unsigned long integers, and sscanf() for a more formatted approach.