Language in C 面接の質問と回答

Question: How do I write a program to convert a string containing number in a hexadecimal form to its equivalent decimal?

Answer: The following program demonstrates this:
main( )
{
char str[] = "0AB" ;
int h, hex, i, n ;
n = 0 ; h = 1 ;
for ( i = 0 ; h == 1 ; i++ )
{
if ( str[i] >= '0' && str[i] <= '9' )
hex = str[i] - '0' ;
else
{
if ( str[i] >= 'a' && str[i] <= 'f' )
hex = str[i] - 'a' + 10 ;
else
if ( str[i] >= 'A' && str[i] <= 'F' )
hex = str[i] - 'A' + 10 ;
else
h = 0 ;
}
if ( h == 1 )
n = 16 * n + hex ;
}
printf ( "nThe decimal equivalent of %s is %d",
str, n ) ;
}
The output of this program would be the decimal equivalent of 0AB is 171.