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read file line by line c

ycomb1nator answered on December 2, 2023 Popularity 9/10 Helpfulness 1/10

answer read file line by line c

read file line by line c

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-1

// The return string is dynamically allocated so free it after each use!
// return exact string, not just a filled buffer!

char *readLine(FILE *file) {

    if (file == NULL) {
        printf("Error: file pointer is null.");
        exit(1);
    }

    int maximumLineLength = 128;
    char *lineBuffer = (char *)malloc(sizeof(char) * maximumLineLength);

    if (lineBuffer == NULL) {
        printf("Error allocating memory for line buffer.");
        exit(1);
    }

    char ch = getc(file); // read first byte/char
    int count = 0;

    while ((ch != '\n') && (ch != EOF)) {
        if (count == maximumLineLength) {
            maximumLineLength += 128;

            // double the size in case of filled up buffer.
            lineBuffer = realloc(lineBuffer, maximumLineLength);
            if (lineBuffer == NULL) {
                printf("Error reallocating space for line buffer.");
                exit(1);
            }
        }

        lineBuffer[count] = ch;
        count++;

        ch = getc(file);
    }

    lineBuffer[count] = '\0'; // size if count + 1 here
    lineBuffer = realloc(lineBuffer, count+1);

    if (lineBuffer[0] == '\0') 
        return NULL;

    return lineBuffer;
}

Popularity 9/10 Helpfulness 1/10 Language c

Source: stackoverflow.com

Tags: c file line-by-line

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Contributed on Dec 02 2023

ycomb1nator

0 Answers Avg Quality 2/10

read file line by line c

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