Different Ways to Compare Strings in C++

This section will discuss the different ways to compare the given strings in the C++ programming language. The comparison of the string determines whether the first string is equal to another string or not. Example: HELLO and Hello are two different strings.

There are different ways to compare the strings in the C++ programming language, as follows:

1. Using strcmp() function
2. Using compare() function
3. Using Relational Operator
4. Using For loop and If statement
5. Using user-defined function

strcmp() function

The strcmp() is a pre-defined library function of the string.h header file. The strcmp() function compares two strings on a lexicographical basis. This means that the strcmp() function starts comparing the first string with the second string, character by character until all characters in both strings are the same or a NULL character is encountered.

Syntax

Parameters:

leftstr: It defines the characters of the left string.

rightstr: It defines the characters of the right string.

Returns:

The leftstr string compares each character with the second string from the left side till the end of both strings. And, if both the strings are equal, the strcmp() function returns strings are equal. Else, the strings are not equal.

Let's create a program to compare strings using the strcmp() function in C++.

Program1.cpp

Output

 String 1:  Welcome to JavaTpoint
 String 2:  Welcome to JavaTpoint

 Both strings are equal.

 String 3:  JavaTpoint
 String 4:  Javatpoint

 The strings are not equal.

compare() function

The compare() function is a pre-defined library function of the C++ language. The compare() function compares two given strings and returns the following results based on the matching cases:

1. If both the strings are the same, the function returns 0.
2. If the character value of the first string is smaller than the second string, the function returns < 0.
3. If the second string is greater than the first string, the function returns greater than 0 or >0.

Syntax

Let's create a simple program to compare two strings using the compare() function in C++.

Program2.cpp

Output

1st Run:
Enter the string 1: Program
 Enter the string 2: program
Program is smaller than program string


2nd Run:
Enter the string 1: APPLE
 Enter the string 2: APPLE
 Both strings are equal.

Relational Operator

It is the operator used to compare two strings or numerical values in C++. C++ has different types of relational operators such as '==', '!=', >, < operator. But here, we use only two operators such as '==' equal to and '!=' not equal to a relational operator to compare the string easily.

Syntax

Compare two strings using the Equal to (==) operator in C++

Equal To (==) operator: It is used to check the equality of the first string with the second string.

Let's create a program to compare strings using the double equal to (==) operator in C++.

Program3.cpp

Output

Enter the String 1:
JavaTpoint
 Enter the String 2:
javatpoint
 String is not equal.

2^nd Execution:

Enter the String 1:
Program
 Enter the String 2:
Program
 String is equal.

Compare two strings using the Not Equal To (!=) Relational Operator

Let's create a program to compare whether the strings are equal or not using the Not Equal To (!=) operator in C++.

Program4.cpp

Output

Enter the String 1:
JAVATpoint
 Enter the String 2:
JavaTPOINT
 String is not equal.

2^nd Run:

Enter the String 1:
HELLO
 Enter the String 2:
HELLO
 String is equal.

Compare two strings using for loop and if statement in C++

Program5.cpp

Output

Enter the String 1:
WELCOME
 Enter the String 2:
WELCOME
 String 1 is equal to String 2

Compare two strings using the User-defined function in C++

Let's create a simple program to compare the first string with another string using the user-defined function in C++.

Program6.cpp

Output

JavaT is not equal to Tpoint string.
Tpoint is greater than JavaT string.
JavaTpoint is equal to JavaTpoint string.