Problem with swapping vector positions

Question

Good morning!

Using Dev C++, I am making the following problem in C:

Make a program in C that reads a 20-position vector of the real type. Replace the first position with the 11th, the 2nd with the 12th, the 3rd with the 13th, ..., the 10th with the 20th. the modified vector.

This is my code that’s not working:

#include<stdio.h>
#include<conio.c>

main () {
    float vet[20], aux;
    int i;

    clrscr();

//entrada dos dados
printf("Favor informar 20 valores: ");
for(i=0;i<20;i++) {
    gotoxy(i*3+2,8);
    scanf("%f", &vet[i]);
}
gotoxy(5,20);

//troca dos vetores
for(i=0;i<20;i++) {
    aux=vet[i];
    vet[i]=vet[19-i];
    vet[19-i]=aux;
}

//saida dos dados
gotoxy(2,12);
printf("Vetor modificado: ");
for(i=0;i<20;i++) {
    gotoxy(i*3+2,14);
    printf("%i", vet[i]);
}

getch();
}

I can’t identify the error. What can it be?

Answer 1

The error is in the loop where you exchange the values. You are exchanging the 1° value with the 20°, the 2° with the 19° and so on. The code below does what is requested.

//troca dos valores
for(i=0;i<10;i++) {
    aux=vet[i];
    vet[i]=vet[10+i];
    vet[10+i]=aux;
}