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giorgi568/htoi.c

Created August 3, 2024 21:53
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  1. giorgi568 created this gist Aug 3, 2024.
    55 changes: 55 additions & 0 deletions htoi.c
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,55 @@
    #include <stdio.h>
    #include <ctype.h>

    int expo(int x, int y);
    int atoi(char c);
    int htoi(char s[]);

    void main() {
    printf("%d\n", htoi("62Fa"));
    }

    int expo(int x, int y){
    int res;
    int i;

    if(y > 0) {
    res = x;
    for(i = 1; i < y; ++i){
    res = res * x;
    }
    } else if(y == 0){
    res = 1;
    }

    return res;
    }

    int atoi(char c){
    return c - '0';
    }

    int htoi(char s[]) {
    int tail = 0;
    int head = 0;
    int res = 0;

    while(s[tail] != '\0'){
    ++tail;
    }

    while(tail > 0) {
    if(isdigit(s[head])){
    res = res + (atoi(s[head]) * expo(16, tail-1));
    }else if(s[head] >= 65 && s[head] <= 70){
    res = res + ((s[head] - 55) * expo(16, tail-1));
    }else if(s[head] >= 97 && s[head] <= 102){
    res = res + ((s[head] - 87) * expo(16, tail-1));
    }

    --tail;
    ++head;
    }

    return res;
    }