hexadecimal string to decimal number C code

#include <stdio.h>
#include <math.h>

int main ()
{
Char ch;//is used to accept an input character
int stack[50];//the hexadecimal decimal corresponding to the stored processing
The number of data in the int top=0;//stack
int decimal=0;//The position of the decimal point in the input string, counting starting at number No. 0
Float num=0;//calculates the last decimal number

printf ("Please enter Hex (0-9,a-f,a-f):");
while ((Ch=getchar ())!= '/n ')
{
if (ch>= ' 0 ' &&ch<= ' 9 ')
Stack[top++]=int (ch-48);
else if (ch>= ' A ' &&ch<= ' F ')
Stack[top++]=int (ch-55);
else if (ch>= ' a ' &&ch<= ' F ')
Stack[top++]=int (ch-87);
else if (ch== '. ') If it's a decimal point
decimal=top;//indicates that data from the decimal data is a small number of parts
else {
printf ("entered illegal data");
return 0;
}
}

while (top)
{
if (decimal!=0&&top>decimal)//Calculation of the decimal part
Num+=stack[--top]/pow (16,top-decimal+1);
Else
Num+=stack[--top]*pow (16,top)//To calculate the whole number of parts
}
printf ("%.4f", num);
GetChar ();
return 1;
}

March 17, 2009, reserved for remembrance.