Thread: To not accept number unless it is in the right range

I'm working on inserting new number into existing string. The code seems to be working fine but it has thrown up a related issue - while trying to make sure that the position in which the new number is to be inserted, I can check only once if the position index is in the correct range but if an incorrect position index is re-entered then the code proceeds with the wrong position number and throws up funny results. How can I keep sending warning messages to the user until the position is entered within correct range? Thanks; the code is as follows:

Code:

#include <stdio.h>  
  
int main()  
{  
    int arr[100];  
    int i, size, num, position, temp_position;  
  
    /* 
     * Reads size and elements of array 
     */  
    printf("Enter size of the array : ");  
    scanf("%d", &size);  
    printf("Enter elements in array : \n");  
    for(i=0; i<size; i++)  
    {  
        scanf("%d", &arr[i]);  
    }  
  
    /* 
     * Read element to insert and position of the element 
     */  
    printf("Enter element to insert : ");  
    scanf("%d", &num);  
    printf("Enter the element position : ");  
    scanf("%d", &temp_position);  
  
    /* 
     * If the position of element is not valid 
     */  
    if(temp_position>size+1 || temp_position<=0)  
    {  
        printf("Invalid position! Please enter position between 1 to %d: "); 
        scanf("%d", &position); 
    }  
    else  
    
    position = temp_position; 
    {      
        /* 
         * Inserts element in array and increases the size of the array 
         */  
        for(i=size; i>=position; i--)  
        {  
            arr[i] = arr[i-1];  
        }  
        arr[position-1] = num;  
        size++;  
  
        /* 
         * Prints the new array after insert operation 
         */  
        printf("Array elements after insertion : ");  
        for(i=0; i<size; i++)  
        {  
            printf("%d\t", arr[i]);  
        }  
    }  
  
    return 0;  
}

Originally Posted by sean_cantab

I can check only once if the position index is in the correct range but if an incorrect position index is re-entered then the code proceeds with the wrong position number and throws up funny results. How can I keep sending warning messages to the user until the position is entered within correct range?

You need to use a loop, which will continue as long as the user enters a value that is out of range.

A "do-while" loop might be a good choice, as this will allow at least one input before checking the loop condition.

Also, be sure you are compiling with maximum warnings:

Code:

main.c|32|warning: too few arguments for format

Another thing - right after your "else", there is a single line of code followed by a block. The "position = temp_position" is the only thing under the "else", so the block afterwards will always be executed. I don't think this is the behavior you want - you might want to ensure that the block is directly after the "else".

Thank you for the suggestion, it worked and also allowed me to get rid of the temp_position variable you mentioned. Here's the updated code:

Code:

#include <stdio.h>  
  
int main()  
{  
    int arr[100];  
    int i, size, num, position;  
  
    /* 
     * Reads size and elements of array 
     */  
    printf("Enter size of the array : ");  
    scanf("%d", &size);  
    printf("Enter elements in array : \n");  
    for(i=0; i<size; i++)  
    {  
        scanf("%d", &arr[i]);  
    }  
  
    /* 
     * Read element to insert and position of the element 
     */  
    printf("Enter element to insert : ");  
    scanf("%d", &num);  
     
    
    do
    
    { 
		printf("Enter the element position : ");  
    scanf("%d", &position); 
		
	}
	
	while 
	
	(position <=0 || position > size + 1);
	
  
    
        for(i=size; i>=position; i--)  
        {  
            arr[i] = arr[i-1];  
        }  
        arr[position-1] = num;  
        size++;  
  
        /* 
         * Prints the new array after insert operation 
         */  
        printf("Array elements after insertion : ");  
        for(i=0; i<size; i++)  
        {  
            printf("%d\t", arr[i]);  
        }  
    }