C Program to Count the Occurrence of Each Character in String

This C Program counts the number of occurrence of each character ignoring the case and prints them.

Here is a source code of the C program to count the number of occurrence of each character in a string ignoring their case and also prints them. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

```
/*
```

 * C Program to Count the Number of Occurrence of

 * each Character Ignoring the Case of Alphabets

```
 * & Display them
```
```
 */
```
```
#include <stdio.h>
```
```
#include <string.h>
```
```
#include <ctype.h>
```
```
 
```
```
struct detail
```
```
{
```
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    char c;
```
```
    int freq;
```
```
};
```
```
 
```
```
int main()
```
```
{
```
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    struct detail s[26];
```
```
    char string[100], c;
```
```
    int i = 0, index;
```
```
 
```
```
    for (i = 0; i < 26; i++)
```
```
    {
```
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       s[i].c = i + 'a';
```
```
       s[i].freq = 0;
```
```
    }
```
```
    printf("Enter string: ");
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    i = 0;
```
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    do
```
```
    {
```
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        fflush(stdin);
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        c = getchar();
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        string[i++] = c;
```
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        if (c == '\n')
```
```
        {
```
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            break;
```
```
        }
```
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        c = tolower(c);
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        index = c - 'a';
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        s[index].freq++;
```
```
    } while (1);
```
```
    string[i - 1] = '\0';
```

    printf("The string entered is: %s\n", string);

```
 
```

    printf("*************************\nCharacter\tFrequency\n*************************\n");

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    for (i = 0; i < 26; i++)
```
```
    {
```
```
        if (s[i].freq)
```
```
        {
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            printf("     %c\t\t   %d\n", s[i].c, s[i].freq);

```
        }
```
```
    }
```
```
 
```
```
    return 0;
```
```
}
```

$ cc allcharfreq.c
$ ./a.out
Enter string: A quIck brOwn fox JumpEd over a lazy dOg
The string entered is: A quIck brOwn fox JumpEd over a lazy dOg
*************************
Character	Frequency
*************************
     a		   3
     b		   1
     c		   1
     d		   2
     e		   2
     f		   1
     g		   1
     i		   1
     j		   1
     k		   1
     l		   1
     m		   1
     n		   1
     o		   4
     p		   1
     q		   1
     r		   2
     u		   2
     v		   1
     w		   1
     x		   1
     y		   1
     z		   1