Problem
In C language, is the program executed, if we use an uninitialized array?
Solution
If we use any uninitialized array, compiler will not generate any compilation and an execution error.
If an array is uninitialized, you may get unpredictable result.
So, it’s better we should always initialize the array elements with default values.
Example Program
Following is the C program of accessing an uninitialized array −
#include <stdio.h>
int main(void){
int a[4];
int b[4] = {1};
int c[4] = {1,2,3,4};
int i; //for loop counter
//printing all alements of all arrays
printf("\nArray a:\n");
for( i=0; i<4; i++ )
printf("arr[%d]: %d\n",i,a[i]);
printf("\nArray b:\n");
for( i=0; i<4; i++)
printf("arr[%d]: %d\n",i,b[i]);
printf("\nArray c:\n");
for( i=0; i<4; i++ )
printf("arr[%d]: %d\n",i, c[i]);
return 0;
}Output
When the above program is executed, it produces the following result −
Array a: arr[0]: 4195872 arr[1]: 0 arr[2]: 4195408 arr[3]: 0 Array b: arr[0]: 1 arr[1]: 0 arr[2]: 0 arr[3]: 0 Array c: arr[0]: 1 arr[1]: 2 arr[2]: 3 arr[3]: 4
Note
If we didn’t initialize an array, by default, it prints garbage values and never show an error.
Consider another C program for accessing an uninitialized array −
Example
#include <stdio.h>
int main(void){
int A[4];
int B[4] ;
int C[4] = {1,2};
int i; //for loop counter
//printing all alements of all arrays
printf("\nArray a:\n");
for( i=0; i<4; i++ )
printf("arr[%d]: %d\n",i,A[i]);
printf("\nArray b:\n");
for( i=0; i<4; i++)
printf("arr[%d]: %d\n",i,B[i]);
printf("\nArray c:\n");
for( i=0; i<4; i++ )
printf("arr[%d]: %d\n",i, C[i]);
return 0;
}Output
When the above program is executed, it produces the following result −
Array a: arr[0]: 4195856 arr[1]: 0 arr[2]: 4195408 arr[3]: 0 Array b: arr[0]: -915120393 arr[1]: 32767 arr[2]: 0 arr[3]: 0 Array c: arr[0]: 1 arr[1]: 2 arr[2]: 0 arr[3]: 0