Wednesday, July 14, 2010

String Literal with Array Subscript Trick

This is a cool trick I just found out recently.

If you have a string literal such as "abcdef", you can interpret that as an array and use the '[]' operator to get the correct character from the string.

For example:

int main() {
for (int i = 9; i >= 0; i--) {
cout << "abcdefghij"[i];
cout << endl;

That will print out "jihgfedcba".

Now knowing this trick (as well as some other minor changes), we can omit a few lines from our hexToString() function in my previous article.

string toHexString(u32 value) {
char str9[9] = {'0'}; // '0' char followed by null bytes
for (int i = 7, pos = 0; i >= 0; i--) {
char dig = (value>>(i*4))&0xf;
if (!dig && !pos) continue;
str9[pos++] = "0123456789abcdef"[dig];
return string(str9);

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