Question

How to print all log lines containing a specific date from a text block in C

Answer 1

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

char **findAllLogsByDate(const char *logs, const char *targetDate, int *count) {
    char *copy = strdup(logs);        // make a modifiable copy
    char *line = strtok(copy, "\n");
    char **matches = NULL;
    *count = 0;

    while (line != NULL) {
        if (strstr(line, targetDate) != NULL) {
            matches = realloc(matches, (*count + 1) * sizeof(char *));
            matches[*count] = strdup(line);
            (*count)++;
        }
        line = strtok(NULL, "\n");
    }

    free(copy);

    return matches;
}

int main(void) {
    const char *logs =
        "01/12/2023 - Log entry one.\n"
        "17/03/2021 - Log entry two.\n"
        "29/07/2019 - Log entry three.\n"
        "05/11/2024 - Log entry four.\n"
        "22/08/2020 - Log entry five.\n"
        "14/02/2018 - Log entry six.\n"
        "30/09/2022 - Log entry seven.\n"
        "11/06/2017 - Log entry eight.\n"
        "03/04/2025 - Log entry nine.\n"
        "05/11/2024 - Log entry ten.\n";

    int count = 0;
    char **results = findAllLogsByDate(logs, "05/11/2024", &count);

    for (int i = 0; i < count; i++) {
        printf("%s\n", results[i]);
        free(results[i]);
    }

    free(results);
    
    return 0;
}



/*
run:

05/11/2024 - Log entry four.
05/11/2024 - Log entry ten.

*/

 

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