Thursday, January 12, 2017

Programming: A lookup table example in C

Sometimes it is better to replace a code snippet performing calculations by a lookup table. The use cases are:
1. When the result of calculation is always a member of predefined set of numbers
2. When input is a set of predefined integers

For such cases it is easy and convenient to define an array and use it. one such example is (the code can be found here):
#include <stdio.h>
int main(void) {
int lookupTable[4][5] = {
{ -1, 9, 4, -1, 0 },
{-1, -1, 9, -1, 4},
{-1, -1, -1, -1, 5},
{-1, -1, -1, -1, 9}
};
int row, columns;
for(row=0; row < 4; row++) {
for(columns = 0; columns < 5; columns++){
printf("Row %d Columns %d Value %d\n", row, columns, lookupTable[row][columns]);
}
}
return 0;
}

No comments:

Post a Comment