RotateMat, C++ (gcc)

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//g++  7.4.0
//rotate matrix: another version of matrix rotation
//
//rotate function code credit goes to John R Hubbard,University of Richmond; read function and test driver code is created by Rezaul Hoque on August 03,2021;contact: jewelmrh @yahoo.com

//note: codes shared by Rezaul Hoque on rextester are not for sale; they are created and shared to facilitate the algorithm learning process; many like Hoque use this platform to practice programming ;Rezaul hopes his contribution helps others to fine tune their learning;

#include <iostream>
using namespace std;
const int n=3;

void rotate(int [][3],const int);

void read(int [][3]);
void read(int a[3][3]){
cout<<"Enter 9 integers,3 per row:\n";
for(int i=0;i<3;i++){
   for(int j=0;j<3;j++)
cin>>a[i][j];
  }
cout<<"Initial matrix:\n";
for(int i=0;i<3;i++){
cout<<"\n";
   for(int j=0;j<3;j++)
cout<<" "<<a[i][j];
  }
}

void rotate(int m[][3],const int n){
int temp[n][n];
int i,j;
for(i=0;i<n;i++){
 for(j=0;j<n;j++)
temp[i][j]= m[n-j-1][i];
   }
for(i=0;i<n;i++){
 for(j=0;j<n;j++)
m[i][j]= temp[i][j] ;
}

for(int i=0;i<3;i++){
cout<<"\n";
   for(int j=0;j<3;j++)
cout<<" "<<m[i][j];
  }
}
int main()
{
int a[3][3];
read(a);
cout<<"\nAfter 90° rotation:\n";

rotate(a,n);
return 0;
}

Show compiler warnings [ + ] Compiler args [ - ] Show input
Compilation time: 0.42 sec, absolute running time: 0.16 sec, cpu time: 0.01 sec, memory peak: 5 Mb, absolute service time: 0,65 sec