Detecting a specific character string

Recently, I had a school project that made me struggle for a week.
I really need help.

My program takes a string input and modifies it to return another string in its upper or lower case version, so far it works. But when I put in :
"This is so exciting (up, 2)" the output stays the same when it should be "This is SO EXCITING"
My point is to be able to handle the case : (up, n), knowing that the word followed by "(up)" must be capitalized.
If below you will find the concerned function.

Thanks in advance !

// modifyUp converts words before (up) to uppercase
func modifyUp(line string) string {
	words := strings.Fields(line)
	var numWords int
	var numbers int

	for i, word := range words {
		if strings.HasSuffix(word, "(up)") && i > 0 {
			// Convert word(s) to uppercase
			numWords = 1
			if strings.Contains(word, ",") {
				// Handle comma-separated words
				numbers, _ = strconv.Atoi(strings.TrimSuffix(strings.Split(word, ",")[1], ")"))
				word = strings.TrimSuffix(word, fmt.Sprintf(",%d)", numbers))
				numWords += numbers
			} else {
				word = strings.TrimSuffix(word, "(up)")
			}
			// Convert preceding word(s) to uppercase
			for j := i - numWords + 1; j <= i; j++ {
				if j >= 0 {
					words[j] = strings.ToUpper(words[j])
				}
			}
			// Replace modified word with original word
			words[i-numWords+1] = word
		}
	}
	return strings.Join(words, " ")

As mentioned in the comment, you are checking for specifically (up) which will not detect (up, 2). An easy way to check this is that you can throw in an fmt.Println(word) at the start of the for loop to validate each word you're checking. In the case of This is so exciting (up, 2), you get

This
is
so
exciting
(up,
2)

As you can see, (up, is found instead of (up). On top of that, 2) is separated from the check.

If we're keeping the same logic that you currently have, a quick fix for this is as followed:

func modifyUp(line string) string {
    words := strings.Fields(line)
    var numWords int

    for i, word := range words {
	    if (strings.HasSuffix(word, "(up)") || strings.HasSuffix(word, "(up,")) && i > 0 {
		    // Convert word(s) to uppercase
		    numWords = 1
		    if strings.Contains(word, ",") {
			    var numbers int

			    // Handle comma-separated words
			    numbers, _ = strconv.Atoi(strings.TrimRight(words[i+1], ")"))

			    words[i] = ""
			    words[i+1] = ""
			    numWords = numbers
		    } else {
			    words[i] = ""
		    }

		    // Convert preceding word(s) to uppercase
		    for j := i - numWords; j <= i; j++ {
			    words[j] = strings.ToUpper(words[j])
		    }
	    }
    }
    return strings.Join(words, " ")
}

I made some extra changes to the code to get it to work once you parsed the up correctly. You can also drop words[i-numWords+1] = word since you're already replacing it in the conversion.

Hope this helps and let me know if you have any following up questions.

I finally found another way

func modifyUp(line string) string {
	words := strings.Fields(line)
	//var numWords int
	var numbers int

	for i, word := range words {
		if word == "(up," && i < len(words)-1 {
			ok := splitWord(words[i+1])
			if ok {
				wr := words[i+1]
				numbers, _ = strconv.Atoi(wr[:len(wr)-1])
				words[i], words[i+1] = "", ""
				for j := i - 1; j >= 0; j-- {
					if numbers == 0 {
						break
					} else {
						words[j] = strings.ToUpper(words[j])
						numbers--
					}
				}
			}
			break
		}
		if word == "(up)" && i > 0 {
			words[i-1] = strings.ToUpper(words[i-1])
			words[i] = ""
		}
	}

	return strings.Join(words, " ")
}

Thank all you for contibutions