Processing an array in C programming

              Single operations which involve entire arrays are not permitted in C. The assignment operations, comparison operations etc can not be carried in entire array; instead it is carried out on an element by element basis. These operations are usually accomplished using loop.

Passing arrays to function

            An entire array can be passed to a function as an argument. To pass an array to a function, the array name must appear by itself, without brackets or subscripts, as an actual argument within the function call. The corresponding formal argument is written in the same manner, though it must be declared as an array within the formal argument declaration. When declaring a one-dimensional array as a formal argument, the array name is written with a pair of empty square brackets. The size of the array is not specified within the formal argument declaration.

Syntax for function call passing array as argument,

          Function_name(array_name);

Syntax for function prototype which accepts array

           Return_type function_name (data_type  array_name[]);

Example:

        Write a program to read 10 numbers and reorders them in ascending order using function.

void ascending(int num[])    {        int i,j,temp;        for(i=0;i<9;i++)         for(j=i+1;j<10;j++)          {           if(num[i]>num[j])            {             temp=num[i];             num[i]=num[j];             num[j]=temp;             }          }       } void main()   {   int nums[10],i,j;   clrscr();   printf("Enter 10 numbers\n");   for(i=0;i<10;i++)     {   scanf("%d",&nums[i]);      }     ascending(nums);   /* function call passing array nums*/      for(i=0;i<10;i++)       printf("\t%d",nums[i]);           getch();      }

When an array is passed to a function, the values of the array elements are not passed to the function. Rather, the array name is interpreted as the address of the first array element. This address is assigned to the corresponding formal argument when the function is called. The formal argument therefore becomes a pointer to the first array element. Thus, array is passed using call by reference. Thus, changing the values in function is also recognized in main function.

An Examples: 

void change(int a[])    {       a[0]=10;   a[1]=20;      a[2]=30;      a[3]=40;     a[4]=50;     } void main()   {   int nums[5]={1,2,3,4,5},i;   clrscr();   printf("Before function call\n");   for(i=0;i<5;i++)       { printf("\t%d",nums[i]); }   change(nums);  printf("\nAfter function call:\n");      for(i=0;i<5;i++)       { printf("\t%d",nums[i]); }           getch();      }

Output:-                              Before function call                                1            2          3          4         5                             After function call                               10          20        30        40       50