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String User Defined Function Examples/Programs

This section contains solved programs with explanation and output on C language String User Defined Functions. The programs under this section are not using any string.h header file's library function.

We will learn to create our own string based function to get the length of the string, to reverse the string, to copy string, compare two strings with ad without checking case, to extract a portion of string (extracting substring), splitting string and many more.

List of String User Defined Functions in C language

Here is the list of some solved programs on strings using User Defined Functions.

1. C program to calculate length of the string.
   This program will read a string from the user and calculate their length using User Defined Function.
2. C program to extract a portion of string (Substring Extracting in C).
   This program will read a string from the user and extract a portion of string (substring from the string) based on given from and to index using User Defined Function.
3. C program to copy one string to another.
   This program will read a string from the user and copy the string in another string variable using User Defined Function. [Implementation of own strcpy() function].
4. C program to convert string into lowercase and uppercase without using library function.
   This program will read a string from the user and convert the string into lowercase and uppercase without using library function. [Implementation of strlwr() and strupr() functions].
5. C program to check whether a substring is present in a given string.
   This program will read a string and a substring (part of the string) and check whether substring present in string or not without using library function.
6. C program to compare two string using case and ignoring case without using library function.
   This program will read and compare two strings using case and ignoring case without using library function.
7. C program to concatenate two strings without using library function.
   This program will read two strings and concatenate them without using library function.
8. C program to reverse a string without using library function.
   This program will read a string and reverse the string without using library function.
9. C program to split string by space into words.
   In this C program, we are going to learn how to split string into words by separating string by spaces?
10. C program to toggle each character of a string.
    In this C program, we are going to learn how to toggle each character of a string? Here, all uppercase characters will be converted into lowercase and all lowercase character will be converted into uppercase.
11. C program to count upper case and lower case characters in a string.
    In this C program, we are counting and printing the total number of uppercase and lowercase characters of a string.
12. C program to count digits, spaces, special characters, alphabets in a string.
    This program will count and print the total number of digits, spaces, special characters and alphabets.