Question

int myatoi(const char* string) {
int i;
i = 0;
while(*string) {
    i = (i << 3) + (i<<1) + (*string -'0');
    string++;
}
return i;
}

int main() {
int i = myatoi("10101");
printf("%d\n",i);
char a = (char)(((int)'0')+i);
printf("%c\n",a);


return 0;
}

my output turns out to be
10101

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how to fix this

should I parse int by int to convert into a char because we can use any c built in functions that can help us convert

Answer 1

What do you expect to have happen?

Your code correctly converts the string "10101" into the integer 10101, and prints it. That looks fine. You then compute 10101+(int)'0' which is probably 10149 (in ascii or unicode, (int)'0' is 48). Converting that to a char probably gives you 165 (or perhaps -91) which probably doesn’t correspond to a printable character on your system, so you get a blank/garbage/missing character.

All is as expected.