C-Program to count vowels in sentence

#include<stdio.h>

#include<string.h>

int main()

{

    int i,vowelcount=0;

    char str[100];

    printf("Enter a string\n");

    gets(str);

    for(i=0;i<strlen(str);i++)

    {

        if(str[i]=='A'||str[i]=='a'||str[i]=='e'||str[i]=='E'||str[i]=='I'

        ||str[i]=='i'||str[i]=='O'||str[i]=='o'||str[i]=='U'||str[i]=='u')

        {

            vowelcount++;

        }

    }

    printf("%d\n",vowelcount);

    return 0;

}

C-Program to count number of times a letter repeated in sentence

#include<stdio.h>

#include<string.h>

int main()

{

int i,count=0;

char c,str[100];

printf("Enter a sentence\n");

gets(str);

printf("Enter a character to know it's repetance in sentence\n");

scanf("%c",&c);

for(i=0;i<strlen(str);i++)

{

    if(str[i]==c)

    {

        count++;

    }

}

printf("Letter %c repeated %d times\n",c,count);

return 0;

}

C-Program to know the frequency of each character in sentence

#include<stdio.h>

#include<string.h>

int main()

{

    int i,k=0,count[26]={0},x;

    char str1[100];

    printf("Enter a sentence\n");

    gets(str1);   

    while(str1[k]!='\0')

    {

        if(str1[k]>='a'&&str1[k]<='z')

        {

            x=str1[k]-'a';

            count[x]++;

        }

        if(str1[k]>='A'&&str1[k]<='Z')

        {

           x=str1[k]-'A';

            count[x]++;

        }

        k++;

    }

    for(i=0;i<26;i++)

    {

        if(count[i]!=0)

        {

            printf("%c occured %d times\n",i+'a',count[i]);

        }      

    }

 return 0;

}