Thread: Trim the text exercise - C

  1. #1
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    Nov 2019

    Trim the text exercise - C

    Hey everyone.

    This is the description of the exercise:

    Write a function that receives a string and prints a "trimmed" version according to the following rules:
    1. All consecutive whitespace is reduced to a single space: spaces, tabs and newlines are removed and replaced by a single space.
    2. All words have the first and last letter removed. A "word" is any sequence of characters that is not whitespace.
    trim_text("some text with a space$$");
    should print:
    om ex it pace$
    The function signature is: void trim_text(char * str)
    Hints: You may use "isspace()" found in ctype.h (already included for you).

    Here is my solution:

    void trim_text(char* str) {
        size_t size = strlen(str);
        if (size <= 2) { // The trimmed string is blank
        char* trimmed = (char*)malloc(sizeof(char) * size - 1); // Without the first and last chars but with null-terminator
        int currIndex = 0;
        str++; // Let's iterate the str from the relevant first char (second one as the first is trimmed)
        while (*str != '\0') {
            if (isspace(*(str + 1))) { // Then this is the end of the word - trim it!
                str++; // Now it points to a space - and we'll increment it to the next non-space char
                while (isspace(*str)) {
                // Now str points to the beginning of the next word
                if (*str != '\0') {
                    str++; // We have to trim the beginning of this new word
                    trimmed[currIndex] = ' ';
                else {
                    trimmed[currIndex] = '\0'; // The trimmed str is ready!
            else if (*(str + 1) == '\0') { // We are at the end ot str
                trimmed[currIndex] = '\0';
            else // We are in the middle of str where the char is not any of spaces
                trimmed[currIndex] = *str;
        printf("%s", trimmed);
    int main()
        trim_text("some text with  a     space$$");
        return 0;
    My output is:
    om ex it<TWO WHITESPACES>pace$
    Whereas the expected one is:
    om ex it<ONLY ONE WHITESPACE>pace$
    Can someone figure the problem in my code out?
    I have been debugging it for a while but I didn't catch the problem...

    Thank you.
    Last edited by HelpMeC; 12-03-2019 at 11:35 AM.

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