Thread: Failure to determine array's maximum

Code:

#include <stdio.h>
#define N 6
int main(void){
    int i,k,v[N];
    printf("Input the vector:\n");
    for(i=0;i<N;i++){
                     printf("Element %d:",i+1);
                     scanf("%d",&v[i]);}
                     printf("\n");
    maxpos(v[N]);
    return 0;
}

int maxpos(int vec[]){
    int k,max,pos;
    max=0;
    for(k=0;k<N;k++){
                     if(vec[k]>vec[k+1]){
                                         max=vec[k];
                                         pos=k;}
                     }
    printf("\n");
    printf("Maximum:%d;\nPos:%d;",max,pos);
    system("pause");
}

When I run this code, regardless of the vector I input, the outcome is invariably the same: Maximum:1 Pos:4

I've check the code up and down but I can't find anything wrong with it.
Can anyone tell me what I'm doing wrong here?

Appreciate.

Code:

                     if(vec[k]>vec[k+1]){

loop condition is k < N, so if k is N-1, k + 1 is N which is out of bound for array vec.since valid indices [0 to N-1] inclusive

Originally Posted by Sebastiani

1) Set 'max' to the first element in the array.
2) Compare 'vec[k]' with 'max', not 'vec[k+1]'.
3) FYI, accessing 'vec[k+1]' on the last iteration will necessarily put you past the bounds of the array...

Very well. I read what you suggested and I agree. However, with the code now corrected in that way, the very same error pops up: Max:1 Pos:4
There's something more to it :|

Code:

#include <stdio.h>
#define N 6
int main(void){
    int i,k,v[N];
    printf("Input the vector:\n");
    for(i=0;i<N;i++){
                     printf("Element %d:",i+1);
                     scanf("%d",&v[i]);}
                     printf("\n");
    maxpos(v[N]);
    return 0;
}

int maxpos(int vec[]){
    int k,max,pos;
    max=vec[0];
    for(k=0;k<N;k++){
                     if(vec[k]>max && vec[k]<N){
                                         max=vec[k];
                                         pos=k;}
                     }
    printf("\n");
    printf("Maximum:%d;\nPos:%d;",max,pos);
    system("pause");
}

Code:

    for(k=0;k<N;k++){
       if(vec[k]>max && vec[k]<N){
           max=vec[k];
           pos=k;} }

See the part I boldfaced for you?
Why do you care about that?

Originally Posted by CommonTater

Code:

    for(k=0;k<N;k++){
       if(vec[k]>max && vec[k]<N){
           max=vec[k];
           pos=k;} }

See the part I boldfaced for you?
Why do you care about that?

I see. It's not necessary since that restriction is already defined within the 'for' loop. I've removed it now, and it still doesn't output what it should. Maybe there's some screw up in the manner in which I wrote the function? Could that be?

Originally Posted by KAUFMANN

I see. It's not necessary since that restriction is already defined within the 'for' loop. I've removed it now, and it still doesn't output what it should. Maybe there's some screw up in the manner in which I wrote the function? Could that be?

Actually, that's not guaranteed by the for loop. You don't care if an element (vec[k]) is less than N, only that the index (k) is less than N.

Your maxpos function should have a return type void since you don't actually return anything.

Also, don't pass in v[N] to maxpos. First, your maxpos function expects an array of ints, so pass in just plain old v. Also, Bayint Naung already mentioned, 0 to N-1 are the only valid indexes. v[N] is trying to access the 7th element of a 6-element array, which is out of bounds and produces undefined behavior.