hexadecimal

#include <stdio.h>
int main() {
    char c[100];
    int n,i;
    n=0;
    printf("Enter Your Hexadecimal:\n");
    scanf("%s",&c);
    for(i=0; c[i]!='\n' && c[i]!=0 ; i++){
            if(c[i]>='0' && c[i]<='9')
                n=n*16+(c[i]-'0');
            else if(c[i]=='A' || c[i]=='a')
                n=n*16+(10);
            else if(c[i]=='B' || c[i]=='b')
                n=n*16+(11);
            else if(c[i]=='C' || c[i]=='c')
                n=n*16+(12);
            else if(c[i]=='D' || c[i]=='d')
                n=n*16+(13);
            else if(c[i]=='E' || c[i]=='e')
                n=n*16+(14);
            else if(c[i]=='F' || c[i]=='f')
                n=n*16+(15);
            else{
                printf("Error:Your number Is Not Valid!");
                return -1;
            }       
    }
    printf("%d",n);
    return 0;
}