The array can be initialized at the same time as declaring as well as the current variable.
Do the initialization of array as follows.

型名 配列名[要素数]={0番の数値,1番の数値,2番の数値,･･･};

 
#include <stdio.h> 

int main(void)  
{
	int array[10] = {42,79,13};  
	
	printf("array[0] = %d\n",array[0]);  
	printf("array[1] = %d\n",array[1]);  
	printf("array[2] = %d\n",array[2]);  
	printf("array[3] = %d\n",array[3]);  
	printf("array[4] = %d\n",array[4]);  
	
	return 0;
}

array[0] = 42
array[1] = 79
array[2] = 13
array[3] = 0
array[4] = 0

 
#include <stdio.h> 

int main(void)  
{
	int array[] = {42,79,13}; /* The number of elements is omitted */. 
	
	printf("array[0] = %d\n",array[0]);  
	printf("array[1] = %d\n",array[1]);  
	printf("array[2] = %d\n",array[2]);  
	
	return 0;
}

It is adjusted to one degree to substitute the value for the array only at the declaration.
For instance, the following substitutions cannot be done.

array = {42,79,13};
array[10] = {42,79,13};

array[0] = 42;
array[1] = 79;
array[2] = 13;

The loop of the for sentence can be used to display all elements of the array.
Only being able to do such a usage is the maximum advantage of the array.
The following program is an example of displaying all the numbers of elements in the array.

 
#include <stdio.h> 

int main(void)  
{
	int array[] = {42,79,13,75,19};  
	int i;  
	
	for (i = 0;i < 5;i++) { 
		printf("array[%d] = %d\n",i,array[i]); 
	}
	
	return 0;
}

array[0] = 42
array[1] = 79
array[2] = 13
array[3] = 75
array[4] = 19

If it is this, it is possible to write easily even by the program that displays the data of 10,000 people.
In changing the sentence in the loop the other, substitute the same value as all elements.
The average of the value substituted for all elements can be easily requested.

It will repeat automatically requesting the number of elements because it is troublesome.
An immediate method of requesting the number of elements can be calculated though is not prepared.

If it is divided by the size of one element for the size of the entire array, the number of elements is understood.
In C language, there is sizeof ([saizuobu]) operator from which the size of the variable and the array is requested.
Use the sizeof operator as follows.

 
sizeof(variable and array identifier)

 sizeof(array) / sizeof(array[0])

 
#include <stdio.h> 

int main(void)  
{
	int array[] = {42,79,13,75,19};  
	int i;  

	for (i = 0;i < sizeof(array) / sizeof(array[0]);i++) { printf("array[%d] = %d\n",i,array[i]); 
	}

	return 0;
}

Use the for sentence to substitute the value of all elements of a certain array for other arrays.

 
#include <stdio.h> 

int main(void)  
{
    int array1[] = {42,79,13,19,41};  
	int array2[] = {1,2,3,4,5};  int i;  
	
	for (i = 0;i < sizeof(array2) / sizeof(array2[0]);i++) { printf("array2[%d] = %d\n",i,array2[i]); 
	}
	
	 Array2[i] =     Array1[i];
	}
	
	for (i = 0;i < sizeof(array2) / sizeof(array2[0]);i++) { printf("array2[%d] = %d\n",i,array2[i]); 
	}
	
	return 0;
}

array2[0] = 1
array2[1] = 2
array2[2] = 3
array2[3] = 4
array2[4] = 5
array2[0] = 42
array2[1] = 79
array2[2] = 13
array2[3] = 19
array2[4] = 41

However, even if the for sentence is not used, the memcpy function can be used.
To use the memcpy function, # include should do the memory.h file.

memcpy(コピー先配列名､コピー元配列名、配列全体のサイズ)

Specify the array identifier by the sizeof operator to copy all elements of the array.
The following program is an example of copying the array by the memcpy function.

 
#include <stdio.h> #include <memory.h> 

int main(void)  
{
	int array1[] = {42,79,13,19,41};  
	int array2[] = {1,2,3,4,5};  
	int i;  
	
	for (i = 0;i < sizeof(array2) / sizeof(array2[0]);i++) { printf("array2[%d] = %d\n",i,array2[i]); 
	}
	
	memcpy(array2,array1,sizeof(array1)); /* All elements of array1 Copy onto array2 */. 
	
	for (i = 0;i < sizeof(array2) / sizeof(array2[0]);i++) { printf("array2[%d] = %d\n",i,array2[i]); 
	}
	
	return 0;
}