Parse Integer Status

Parsing code should return an explicit status instead of assuming text is valid.

parse_int_status.c

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

int parseInt(const char *text, int *outValue) {
    char *end = 0;
    long value = strtol(text, &end, 10);

    if (end == text || *end != '\0') {
        return 0;
    }
    if (value < -100 || value > 100) {
        return 0;
    }

    *outValue = (int)value;
    return 1;
}

int main(void) {
    int inputCase = ;
    const char *text = "42";
    if (inputCase == 1) {
        text = "17x";
    } else if (inputCase == 2) {
        text = "150";
    }

    int value = 0;
    int ok = parseInt(text, &value);

    printf("inputCase=%d ok=%d value=%d\n", inputCase, ok, value);
    return 0;
}

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

int parseInt(const char *text, int *outValue) {
    char *end = 0;
    long value = strtol(text, &end, 10);

    if (end == text || *end != '\0') {
        return 0;
    }
    if (value < -100 || value > 100) {
        return 0;
    }

    *outValue = (int)value;
    return 1;
}

int main(void) {
    int inputCase = ;
    const char *text = "42";
    if (inputCase == 1) {
        text = "17x";
    } else if (inputCase == 2) {
        text = "150";
    }

    int value = 0;
    int ok = parseInt(text, &value);

    printf("inputCase=%d ok=%d value=%d\n", inputCase, ok, value);
    return 0;
}

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

int parseInt(const char *text, int *outValue) {
    char *end = 0;
    long value = strtol(text, &end, 10);

    if (end == text || *end != '\0') {
        return 0;
    }
    if (value < -100 || value > 100) {
        return 0;
    }

    *outValue = (int)value;
    return 1;
}

int main(void) {
    int inputCase = ;
    const char *text = "42";
    if (inputCase == 1) {
        text = "17x";
    } else if (inputCase == 2) {
        text = "150";
    }

    int value = 0;
    int ok = parseInt(text, &value);

    printf("inputCase=%d ok=%d value=%d\n", inputCase, ok, value);
    return 0;
}

parse status `strtol` can report where parsing stopped so the program can reject partial input.

range limit A valid number can still be outside the range accepted by the program.