C :

#include<stdio.h>
int main(){
	int n,i,j;
	scanf("%d",&n);
	int a[n][n];
	for(i=0;i<n;i++){
		for(j=0;j<n;j++){
			if(i==j){
				a[i][j] = 1;
			}else{
				a[i][j] = 0;
			}
		}
	}
	for(i=0;i<n;i++){
		for(j=0;j<n;j++){
			printf("%3d",a[i][j]); 
		}
		printf("%s","\n");
	}
	return 0;
}

C++ :

#include <iostream>
#include <iomanip>
#include <cmath>
#include <cstdio>

using namespace std;

int main(){
    int n,i,j,a[110][110];
    cin>>n;
    for(i=1;i<=n;i++){
    	for(j=1;j<=n;j++){
    		if(i!=j)
    		a[i][j]=0;
    		else
    		a[i][j]=1;
		}
	}
	for(i=1;i<=n;i++){
		for(j=1;j<=n;j++){
			cout<<setw(3)<<a[i][j];
		}
		
		cout<<endl;
	}
}

Pascal :

var
     a,i,max,n,k:longint;
     b:array[1..10,1..10] of longint;
   begin
      readln(n);
      for i:=1 to 10 do b[i,i]:=1;
      for i:=1 to n do
      begin
        for k:=1 to n do write(b[i,k]:3);
        writeln;
      end;
end.

Java :

import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner sc= new Scanner(System.in);
		int b= sc.nextInt();
		int[][] a =new int[b][b];
		
		int s=0;
		
		for(int n=0;n<a.length;n++){
			for(int m=0;m<a[n].length;m++){
				if(n==s&&m==s){
					a[n][m]=1;
					s++;
				}
			}
		}
				
		for(int n=0;n<b;n++){
			for(int m=0;m<b;m++){
				System.out.printf("%3d",a[n][m]);
			}
			System.out.println("");
		}
		
		
	}

}

Python :

def getList(m,n):
    '''
      m 行数
      n 列数
      返回的是m行n列的二维数组，默认值为0
    '''
    ma = [ [0 for i in range(n)] for i in range(m) ]
    return ma
def printList(arr):
    for i in arr:
        for j in i:
            print('%3d' %(j),end='')
        print();
n=int(input())
arr = getList(n,n)
for i in range(0,n):
    for j in range(0,n):
        if i==j:
            arr[i][j] = 1
        # else:
        #     arr[i][j] = 0
       
printList(arr)