C++ Program to Toggle Cases in a String

This is a C++ Program to Toggle Cases in a String.

Problem Description

The program takes a string and changes the cases of the string characters.

Problem Solution

1. The program takes a string.
2. Using ctype functions, uppercase characters are converted to lowercase and vice versa.
3. If entered string is not alphabetical, program is exited.
4. The converted string is printed.
5. Exit.

C++ Program/Source code

Here is the source code of C++ Program to Toggle Cases in a String. The program output is shown below.

```
#include<iostream>
```
```
#include<string.h>
```
```
#include<ctype.h>
```
```
using namespace std;
```
```
int main ()
```
```
{
```
```
    char str[50];
```
```
    cout << "Enter a string : ";
```
```
    gets(str); 
```

    for (int i = 0; str[i] != '\0'; i++)

```
    {
```
```
        if (isalpha(str[i]))
```
```
        {
```
```
            if (islower(str[i]))
```

                str[i] = toupper(str[i]);

```
            else
```

                str[i] = tolower(str[i]);

```
        }
```
```
        else
```
```
	{
```

            cout << "Entered string is not alphabetical.";

```
            exit(0);
```
```
        }
```
```
    }
```

    cout << "Resultant string : " << str;

```
}
```

Program Explanation

1. The user is asked to enter a string. It is stored in the character variable ‘str’.
2. Using a for loop, each character in the string is checked.
3. If it is an alphabet, it is further checked if it’s uppercase or lowercase.
4. If the character is uppercase, it is converted to lowercase, else vice versa.
5. If character is not an alphabet, the program is exited.
6. The converted string is then printed.

Runtime Test Cases

Case 1 :
Enter a string : sPANISH
Resultant string : Spanish
 
Case 2 :
Enter a string : halo25
Entered string is not alphabetical.
 
Case 3 :
Enter a string : EUPHORIA
Resultant string : euphoria

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