Unable to open this code using GCC, what do I need to change

#include

int main(void){

int inChar, outChar;

while ((inChar = getchar()) != EOF){

int number;

if ((inChar >= 'A' && inChar <= 'Z') || (inChar >= 'a' && inChar <= 'z')) {

number = inChar & 0x1F;

number = (((number << 4) | ((number & 2) << 2) | (number & 4) | ((number & 8) >> 2)) | (number >> 4)) & 0x1F;

outChar = (inChar & 96) | number;

}

putchar(outChar);

}

return 0;

}