Wdmatch

What's wdmatch

Wdmatch is a function that takes two string and checks whether it is possible to write the first string with characters from the second string. This rewrite must respect the order in which these characters appear in the second string.

PrintStr function

We write a PrintStr function that will print a string we will give to it.

func PrintStr(s string) {
  for i := 0; i < len(s); i++ {
    z01.PrintRune(rune(s[i]))
  }
  z01.PrintRune('\n')
}

Wdmatch step by step

First step

First, we need to check the numbers of arguments we have.
If it's something different that 3 (2 args and the name of the file), then we just end the programm without doing anything.

if len(os.Args) != 3 {
    return
}

Second step

We then initialize 2 variables that will store os.Args[1] and os.Args[2].
We also create a variable that will store our result.

arg1 := os.Args[1]
arg2 := os.Args[2]
result := ""

Third step

We need to iterate over our first argument.

for i := 0; i < len(arg1); i++ {
}

Inside that loop we want to iterate over the second argument.
That way for each letter, we are going to iterate over the second argument to look for that specific letter.

for i := 0; i < len(arg1); i++ {
    for j := index; j < len(arg2); j++ {
    }
}

Fourth step

We then need to check if the letter from the first argument match the letter from the second argument.
If that's the case then we need to add that letter to a result variable.

if arg1[i] == arg2[j] {
    result += string(arg1[i])
}

Fifth step

This rewrite must respect the order in which these characters appear in the second string.
Because of that, everytime two letters match, we need to go from the index of the next letter we found.
So the j loop won't start at 0 everytime but a given variable that will change when the letters will match.

index := 0
for i := 0; i < len(arg1); i++ {
    for j := index; j < len(arg2); j++ {
        if arg1[i] == arg2[j] {
            result += string(arg1[i])
            index = j
            break
        }
    }
}

So the next j loop, it will store previous index.
Also once we found a letter, we need to break so we look for another letter.

Sixth and final step

We then compare the result variable to the original os.Args[1].
If those two are equal, that means that the os.Args[1] is contained in the os.Args[2].

if result == arg1 {
    PrintStr(result)
}

We then print the result, otherwise we don't print anything.

Full code

package main

import "os"

func PrintStr(s string) {
  for i := 0; i < len(s); i++ {
    z01.PrintRune(rune(s[i]))
  }
  z01.PrintRune('\n')
}

func WdMatch() {
    if len(os.Args) != 3 {
        return
    }
    arg1 := os.Args[1]
    arg2 := os.Args[2]
    index := 0
    result := ""
    for i := 0; i < len(arg1); i++ {
        for j := index; j < len(arg2); j++ {
            if arg1[i] == arg2[j] {
                result += string(arg1[i])
                index = j
                j = len(arg2)
            }
        }
    }
    if result == arg1 {
        PrintStr(result)
    }
}