From QB64.org wiki
The ASC statement allows a QB64 program to change a character at any position of a STRING variable.
- ASC(stringExpression$[, position%]) = code%
- The stringExpression$ variable's value must have been previously defined and cannot be an empty string ("").
- position% is optional. If no position is used, the leftmost character at position 1 is assumed.
- position% cannot be zero or greater than the string's length or an Illegal function error will occur.
- The ASCII replacement code% value can be any INTEGER value from 0 to 255.
- Some ASCII control characters will not PRINT a character or may format the SCREEN. _PRINTSTRING can print them graphically.
Example: Demonstrates how to change existing text characters one letter at a time.
ABC A C ASC