patterncMinor

Program to tell which if any of three numbers is in the middle

Submitted by: @import:stackexchange-codereview·Mar 10, 2026·

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threetheanynumbersprogramtellwhichmiddle

Problem

I wrote this program, and it does what it asks, but it's so big and ugly. What can I change?

Some examples:

a  b  c --->
5  1  12   a is between b and c
5  12 1    a is between c and b
5  5  2    there is no gap

This was in an example of a test that is supposed to be small, so that's why I'm asking if there is another way.

#include 
#include 
#include 

int main (void){
int a,b,c;

printf("Inserir 3 números: "); //its in portuguese, insert 3 numbers
scanf("%i %i %i",&a,&b,&c);

if(a==b||b==c||a==b){
    printf("não há intervalo\n"); //there is no gap
    exit(0);
}

int maior, meio, menor,flag,flag2,flag3;

maior=a; //maior means biggest
flag=1;
if(maiorb){
    menor=b;
    flag3=2;
}if(menor>c){
    flag3=3;        
}

if(flag2==1)
    printf("o a entre [");
if(flag2==2)
    printf("o b entre [");
if(flag2==3)
    printf("o c entre [");

if(flag3==1)
    printf("a e ");
if(flag3==2)
    printf("b e ");
if(flag3==3)
    printf("c e ");

if(flag==1)
    printf("a]\n");
if(flag==2)
    printf("b]\n");
if(flag==3)
    printf("c]\n");

return 0;
}

Solution

-
Well, first of all, consider adopting one of the myriad common indentation-styles and use it consistently.

Doing so will make your code far easier to read and write.

-
You should test whether you really got three numbers.

Currently, you don't, which leads to UB.

-
If in doubt, sort.

That eliminates an astonishing number of problems.

-
You aren't using anything from `

, so don't include it.

-

exit(0); and return 0; have nearly the same effect when done in main

.

The only differences are when

main

 is called recursively, and we won't do such an abomination outside the IOCCC. (Or if we change to a different language, like C++, but who would do that?)

#include 
#include 

typedef struct namednumber {int num; char name; } namednumber;

static int comp_namednumber(const void* pa, const void* pb) {
    int a = ((namednumber*)pa)->num,
        b = ((namednumber*)pb)->num;
    return (a > b) - (a < b);
}

int main() { // No need for void in the parameter-list, this is a definition
    int a, b, c;
    printf("Please enter three numbers:\n");
    if(3 != scanf("%i %i %i", &a, &b, &c)) {
        printf("You didn't enter three numbers. Aborting.\n");
        return EXIT_FAILURE;
    }

    if(a == b || b == c || c == a) {
        printf("There is no gap.");
        return 0;
    }

    namednumber data[] = {{a,'a'},{b,'b'},{c,'c'}};
    qsort(data, 3, sizeof *data, comp_namednumber);
    printf("%c is between %c and %c\n", data[1].name, data[0].name, data[2].name);

    return 0; // This line is implicit in C99+
}


Actually, getting out

qsort` is severe overkill, so here with a standard sorting-network:

#include 
#include 

static void sort2(int* a, char* na, int* b, char* nb) {
    if(*a < *b) return;
    int t = *a;
    *a = *b;
    *b = t;
    char nt = *na;
    *na = *nb;
    *nb = nt;
}

int main() {
    int a, b, c;
    printf("Please enter three numbers:\n");
    if(3 != scanf("%i %i %i", &a, &b, &c)) {
        printf("You didn't enter three numbers. Aborting.\n");
        return EXIT_FAILURE;
    }

    if(a == b || b == c || c == a) {
        printf("There is no gap.");
        return 0;
    }

    char na = 'a', nb = 'b', nc = 'c';
    sort2(&a, &na, &b, &nb);
    sort2(&a, &na, &c, &nc);
    sort2(&b, &nb, &c, &nc);
    printf("%c is between %c and %c\n", nb, na, nc);
}

Code Snippets

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

typedef struct namednumber {int num; char name; } namednumber;

static int comp_namednumber(const void* pa, const void* pb) {
    int a = ((namednumber*)pa)->num,
        b = ((namednumber*)pb)->num;
    return (a > b) - (a < b);
}

int main() { // No need for void in the parameter-list, this is a definition
    int a, b, c;
    printf("Please enter three numbers:\n");
    if(3 != scanf("%i %i %i", &a, &b, &c)) {
        printf("You didn't enter three numbers. Aborting.\n");
        return EXIT_FAILURE;
    }

    if(a == b || b == c || c == a) {
        printf("There is no gap.");
        return 0;
    }

    namednumber data[] = {{a,'a'},{b,'b'},{c,'c'}};
    qsort(data, 3, sizeof *data, comp_namednumber);
    printf("%c is between %c and %c\n", data[1].name, data[0].name, data[2].name);

    return 0; // This line is implicit in C99+
}

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

static void sort2(int* a, char* na, int* b, char* nb) {
    if(*a < *b) return;
    int t = *a;
    *a = *b;
    *b = t;
    char nt = *na;
    *na = *nb;
    *nb = nt;
}

int main() {
    int a, b, c;
    printf("Please enter three numbers:\n");
    if(3 != scanf("%i %i %i", &a, &b, &c)) {
        printf("You didn't enter three numbers. Aborting.\n");
        return EXIT_FAILURE;
    }

    if(a == b || b == c || c == a) {
        printf("There is no gap.");
        return 0;
    }

    char na = 'a', nb = 'b', nc = 'c';
    sort2(&a, &na, &b, &nb);
    sort2(&a, &na, &c, &nc);
    sort2(&b, &nb, &c, &nc);
    printf("%c is between %c and %c\n", nb, na, nc);
}

Context

StackExchange Code Review Q#109487, answer score: 6

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