Algorithm

  1. Input:

    • Accept the main string (mainString) and the substring (subString) as input.

  2. Initialization:

    • Initialize a variable (isSubstringFound) to false. This variable will be used to track whether the substring is found in the main string.

  3. Iterate Over the Main String:

    • Use a loop to iterate over each character in the main string.
    • For each character, check whether the substring matches the characters starting from the current position in the main string.

  4. Substring Matching:

    • If a match is found, set isSubstringFound to true and break out of the loop.

  5. Output:

    • After the loop, check the value of isSubstringFound.
    • If isSubstringFound is true, print or return a message indicating that the substring is present in the main string.
    • If isSubstringFound is false, print or return a message indicating that the substring is not found in the main string.

 

Code Examples

#1 Code Example- Check String with includes()

Code - Javascript Programming

// program to check if a string contains a substring

// take input
const str = prompt('Enter a string:');
const checkString = prompt('Enter a string that you want to check:');

// check if string contains a substring
if(str.includes(checkString)) {
    console.log(`The string contains ${checkString}`);
} else {
    console.log(`The string does not contain ${checkString}`);
}
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Output

x
–
+
cmd
Enter a string: JavaScript is fun
Enter a string that you want to check: fun
The string contains fun

#2 Code Example- Check String with indexOf()

Code - Javascript Programming

// program to check if a string contains a substring

// take input
const str = prompt('Enter a string:');
const checkString = prompt('Enter a string that you want to check:');

// check if string contains a substring
if(str.indexOf(checkString) !== -1) {
    console.log(`The string contains ${checkString}`);
} else {
    console.log(`The string does not contain ${checkString}`);
}
Copy The Code & Try With Live Editor

Output

x
–
+
cmd
Enter a string: JavaScript is fun
Enter a string that you want to check: fun
The string contains fun
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Demonstration

JavaScript Program to Check Whether a String Contains a Substring-DevsEnv

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