Question

How to move the first word to the end of a string in C

Answer 1

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char* move_first_word_to_end_of_string(const char *s) {
    char *temp = malloc(strlen(s) + 1);
    strcpy(temp, s);

    char *parts[64];
    int count = 0;

    char *token = strtok(temp, " ");
    while (token != NULL) {
        parts[count++] = token;
        token = strtok(NULL, " ");
    }

    char *first = parts[0];
    for (int i = 0; i < count - 1; i++)
        parts[i] = parts[i + 1];
    parts[count - 1] = first;

    char *result = malloc(strlen(s) + 1);
    result[0] = '\0';

    for (int i = 0; i < count; i++) {
        strcat(result, parts[i]);
        if (i < count - 1) strcat(result, " ");
    }

    free(temp);
    
    return result;
}

int main() {
    char s[] = "Would you like to know more? (Explore and learn)";
    
    char *out = move_first_word_to_end_of_string(s);
    
    printf("%s\n", out);
    free(out);
    
    return 0;
}



/*
run:

you like to know more? (Explore and learn) Would

*/

 

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Answer 2

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int split_words(const char *s, char *parts[], int max_parts, char **copy_out) {
    char *copy = malloc(strlen(s) + 1);
    strcpy(copy, s);

    int count = 0;
    char *token = strtok(copy, " ");
    while (token && count < max_parts) {
        parts[count++] = token;
        token = strtok(NULL, " ");
    }

    *copy_out = copy;   // caller must free(*copy_out)
    
    return count;
}

char* move_first_word_to_end_of_string(const char *s) {
    char *parts[64];
    char *copy;
    int count = split_words(s, parts, 64, &copy);

    char *first = parts[0];
    for (int i = 0; i < count - 1; i++)
        parts[i] = parts[i + 1];
    parts[count - 1] = first;

    char *result = malloc(strlen(s) + 1);
    result[0] = '\0';

    for (int i = 0; i < count; i++) {
        strcat(result, parts[i]);
        if (i < count - 1) strcat(result, " ");
    }

    free(copy);
    
    return result;
}

int main() {
    char s[] = "Would you like to know more? (Explore and learn)";
    char *out = move_first_word_to_end_of_string(s);
    
    printf("%s\n", out);
    free(out);
    
    return 0;
}



/*
run:

you like to know more? (Explore and learn) Would

*/

 

70+ SQL courses for beginners and professionals