Take input into a string and count the number of capital letters, small letters, digits and special symbols in it.
  #include <stdio.h>

int main(void)
{
char str[80];
int x, cap, small, dig, sym;

printf("\nEnter a string : ");
gets(str);

x = cap = small = dig = sym = 0;

for( ; str[x] != '\0' ; x++)
{
if(str[x] >= 'A' && str[x] <= 'Z') cap++;
else if(str[x] >= 'a' && str[x] <= 'z') small++;
else if(str[x] >= '0' && str[x] <= '9') dig++;
else sym++;

}

printf("\nCapital letters %d\nSmall letters %d", cap, small);
printf("\nDigits %d\nSpecial symbols %d", dig, sym);

return 0;
}