We want a function that each time is called returns a character according to times called.
eg.
Called 1st time: will return ‘a’
Called 2nd time: will return ‘b’
Called 3rd time: will return ‘c’
.
.
.
Called 26th time: will return ‘z’
Called 27th time: will return ‘a’
and so on….

1
2
3
4
5
6
7
int f(void){
    static char ch ='a'-1;
    if(ch=='z')
        ch='a'-1;
    ch++;
    return ch;
}