Unresolved external symbol error when compiling [duplicate] - c++

Question

This question already has answers here:
What is an undefined reference/unresolved external symbol error and how do I fix it?
(39 answers)
Closed 7 years ago.
when ever am trying to compile it, i get an error message
unresolved external symbol "void __cdecl showarray(int * const,int)"
am not sure what i am doing wrong? what should I do, my code looks like this
#include<iostream>
#include<string>
using namespace std;
void sortArray(int [], int );
void showarray(int [],int );
int main(){
int endtime[10] = { 70, 38, 8, 101, 11, 127, 313, 14, 16, 127 };
cout << "unsorted" << endl;
showarray(endtime, 10);
sortArray(endtime, 10);
cout << "the sorted value are :" << endl;
showarray(endtime, 10);
return 0;
}
void sortArray(int array[], int size){
bool swap;
int temp;
do{
swap = false;
for (int count = 0; count < (size - 1); count++){
if (array[count] > array[count+1]){
temp = array[count];
array[count] = array[count + 1];
array[count + 1] = temp;
swap = true;
}
}
} while (swap);
}
void showarray(const float array[], int size){
for (int i = 0; i < size; i++)
cout << array[i] <<" "<< endl;
}

Answer 1

At first you declared function
void showarray(int [],int );
but defined function
void showarray(const float array[], int size)
{
//...
}
Change the both declaration and the definition like
void showArray( const int [], int );
^^^^^^^^^ ^^^^^^^^^^^^
For example (the function definition)
void showArray( const int array[], int size )
{
for ( int i = 0; i < size; i++ )
{
cout << array[i] << ' ';
}
cout << endl;
}
And do not forget to change function calls using name showArray.
Take into account that the variable temp should be declared inside the if statement. Also you could use standard function std::swap as for example
std::swap( array[count], array[count+1] );
The program can look like
#include <iostream>
void sortArray( int a[], size_t n )
{
while ( !( n < 2 ) )
{
size_t last = 0;
for ( size_t i = 1; i < n; i++ )
{
if ( a[i] < a[i-1] )
{
int temp = a[i];
a[i] = a[i-1];
a[i-1] = temp;
last = i;
}
}
n = last;
}
}
void showArray( const int a[], size_t n )
{
for ( size_t i = 0; i < n; i++ ) std::cout << a[i] << ' ';
std::cout << std::endl;
}
int main()
{
const size_t N = 10;
int endtime[N] = { 70, 38, 8, 101, 11, 127, 313, 14, 16, 127 };
std::cout << "unsorted: ";
showArray( endtime, N );
sortArray( endtime, N );
std::cout << " sorted: ";
showArray( endtime, N );
}
Its output is
unsorted: 70 38 8 101 11 127 313 14 16 127
sorted: 8 11 14 16 38 70 101 127 127 313
With using standard function std::swap the function sortArray can be more compact and clear
void sortArray( int a[], size_t n )
{
while ( not ( n < 2 ) )
{
size_t last = 0;
for ( size_t i = 1; i < n; i++ )
{
if ( a[i] < a[i-1] )
{
std::swap( a[i], a[i-1] );
last = i;
}
}
n = last;
}
}

Answer 2

You are declaring a
void showarray(int [],int );
but defining a
void showarray(const float array[], int size)
Both are not the same. At the point the compiler tries to compile the function call, he only knows about the first one and uses this. But the linker can only find the second one, which is why he produces an error.

Answer 3

Your function declaration needs to match your function definition:
void showarray(int [],int );
And
void showarray(const float array[], int size){
for (int i = 0; i < size; i++)
cout << array[i] <<" "<< endl;
}
Need to have matching function signatures.