Convert a hexadecimal number to an integer in decimal format.

Previously, the hexadecimal format was converted to decimal format. The hexadecimal format was always first converted to binary format, and then converted to decimal format. Today I see a question: convert a hexadecimal number into an integer. Searching on the internet found that in addition to this conversion, it can also be converted to decimal like binary, for example: Binary 110, it can be 1*2 ^ 2 + 1*2 ^ 1 + 0*2 ^ 0 = 6. In fact, the hexadecimal format is converted to decimal format:

For example, F5 is converted to decimal: F (15) * 16 ^ 1 + 5*16 ^ 0 = 245;

In this way, you can easily write code by converting a hexadecimal number into a decimal number:

String STR = "13abf ";

Intlen = Str. length;

INTSUM = 0;

For (INTI = 0; I <Len; I ++ ){

Char c = Str. charat (len-1-i );

Int n = character. digit (C, 16); // calculates the hexadecimal value of C.

Sum + = N * (1 <(4 * I ));

}