Write a program to convert uppercase to lower case and vice versa of a given string or sentence

This is a C program to replace lowercase characters by uppercase & vice-versa.

This program accepts the sentence and replaces lowercase characters by uppercase & vice-versa.

1. Take the sentence as input. 2. Using (islower()? toupper():tolower()) function replace lowercase characters by uppercase & vice-versa.

3. Print the output and exit.

Here is source code of the C program to replace lowercase characters by uppercase & vice-versa. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

1. /*
2.  * C program to read an English sentence and replace
3.  * lowercase characters by uppercase and vice-versa.
4.  * Output the given sentence as well as the converted
5.  * sentence on two different lines.
6.  */
7. #include <stdio.h>
8. #include <ctype.h>
9.  
10. void main()
11. {
12. char sentence[100];
13. int count, ch, i;
14.  
15. printf("Enter a sentence \n");
16. for (i = 0;(sentence[i] = getchar()) != '\n'; i++)
17. {
18. ;
19. }
20. sentence[i] = '\0';
21. /* shows the number of chars accepted in a sentence */
22. count = i;
23. printf("The given sentence is : %s", sentence);
24. printf("\n Case changed sentence is: ");
25. for (i = 0; i < count; i++)
26. {
27. ch = islower(sentence[i])? toupper(sentence[i]) :
28. tolower(sentence[i]);
29. putchar(ch);
30. }
31. }

1. Take an an English sentence as input and store it in the array sentence[]. 2. Copy the last letter’s position in the array to the variable count. 3. Using for loop and (islower()? toupper():tolower()) function replace lowercase characters by uppercase & vice-versa. Store this in the variable ch.

4. Print the variable ch as output and exit.

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Enter a sentence wELCOME tO sANFOUNDRY The given sentence is : wELCOME tO sANFOUNDRY Case changed sentence is: Welcome To Sanfoundry

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In this tutorial, we will see how to convert uppercase to lowercase in C. It is very easy to convert uppercase to lowercase in c.

Let’s say if you have any character in uppercase, you can simply convert it by just adding 32 to its ascii value.

In similar way, you can substract 32 from ascii character to convert lowercase to uppercase.

Let’s write complete program to convert uppercase to lowercase and vice versa.

printf("\n\nEnter The String: ");     // Calculating length of input string         if (str[i]>=65 && str[i]<=90)         else if (str[i] >= 97 && str[i] <= 122)     printf("\nConverted String(Lower/Upper) Is: %s\n",str);

Output:

Enter The String: code2master

Converted String(Lower/Upper) Is: CODE2MASTER

Enter The String: CODE2MASTER

Converted String(Lower/Upper) Is: code2master

That’s all about convert uppercase to lowercase and vice versa.