Size of String Variable in C
In the world of programming specially when encountering C language programming, string variables has often been the most widely used concept in several programs and have a lot of applications as well. Strings are a sequence of characters that together form a textual data or sentences or even a group of sentences. Understanding the size of string variables can be helpful in memory management and avoiding any pitfalls that can lead to runtime errors or any weird behaviour of the program. In this tutorial, we will learn more about the size of the string variable.
Learning about the String Variable in C language
In C language, string is often represented as an array of character. Each of the given character in the arrays points to a particular element in the string. When we want to reach the end of the string, we can use the null string stating as '\0'. We will see an example to understand this concept more clearly.
Char data [5] = {'T' , 'A', 'N', 'Y', 'A', '\0'};
We can also initialize a string by using double quotes as well. For example: -
Char data[] = "TANYA";
In this example, the array automatically includes the null character and determines the size of the array by counting the number of elements present in the array.
Estimating the size of the String
To assess the size of the string, one must grasp the dynamics of functionality of the strings and also the manner in which the memory is assigned to it. In order to determine the size of the data type "SizeOf" operator is used, which gives a direct method in evaluating the size of the data types. While dealing with the strings, its crucial to keep track of the differences between the array and the string.
Char data[] = "Tanya"; Size_t size = sizeof(data);
Many people confuse size with the length of the string and get confused but size returns the actual size of the string in bytes including the null terminator. So, in the above example the size of the string would be 6( 5 characters + 1 null terminator). In case someone wants to achieve the length of the string then they can simply use "strlen" function and it will give them the desired result.
Dynamic Memory Allocation of the Strings
In C language, dynamic memory allocation using the functions such as malloc and calloc is common especially when we must deal with strings of variable or unknown length. When allocating dynamic memory for strings its important to consider space for both the characters and the null terminator.
For example: -
#include <stdlib.h> #include <string.h> #include <stdio.h> int main() { char *msg = (char*)malloc(6); strcpy(msg, "TANYA"); printf("Message: %s\n", msg); free(msg); return 0; }
Output:
In the above example, "msg" is a dynamically allocated array of size 6 allocated to the characters, accounting for 5 characters in the array and + 1 for the null terminator. We must always make sure that the allocated space should be sufficient for both the null terminator and the characters of the string to avoid buffer overflow issues.
Consequences and Common Mistakes
Having a deep knowledge of size of string variables is very crucial to avoid mistakes and to provide error free coding program in C language. One of the most common mistakes that all beginner or programmers make is to take accountability for the null terminator which always poses a problem. Failing to include the same or mismanaging the same can often result in undefined behaviour.
Char incorrectmsg[5] = "TANYA";
In the above example, incorrectmsg doesn't have the space for the null terminator which will result in potential errors or undefined behaviour when manipulating or even printing the string. We must always make sure to have proper space for both the characters and the null terminator to properly handle the string.
Key Takeaways
Understanding the concept of the size of the string variable can be quite handful as it involves various aspects of memory allocation and representing the strings as the arrays of characters. The size of any given string involves both the characters, and the null terminator and careful considerations have to be taken in order to avoid any mistakes or coding error.