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Passing in as a string and then testing to see if it is an integer

I'm trying to pass in a variable as a string and then test it to see if it is an integer, if it is then I want to store it into an array of structures. I am a little lost as to how to set all this up.

#include <ctype.h>
#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <stdio.h>

struct customers
{
	int cust_id;
	char cust_name[20];
	static char states [50][3];
	char discount;
	double balance_due;
	int order_out;
};
struct myRecords
{
	customers rec[20];
};

using namespace std;

int is_int(char prompt[50]);

int main()
{
	int cust_id;
	myRecords table, *point_table;
	point_table = &table;

	cust_id = is_int("Please enter a customer id: ");

}//end of main

/**************************************
*Function to test if it is an integer *
**************************************/
int is_int(char prompt[50], struct myRecords* table)
{
	int x = 0;
	int y = 0;
	int i;
	x < strlen(prompt);
	if(!isdigit(prompt[x]))
		return 0;
	else
		gets(prompt);
		i = atoi(prompt);
		i = table->rec[y].cust_id;
		return 1;
}

Open in new window

phoffric

x < strlen(prompt);
-- this is an expression; no value is changed
-- did you mean:
x =strlen(prompt);

Here is a discussion on testing whether a string is a number:
http://forums.devarticles.com/c-c-help-52/checking-if-string-is-a-number-or-not-57342.html

SOLUTION

Superdave

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reesee324

ASKER

This is what I have now but I keep getting an external error. My other problem is I don't understand how to store that variable into cust_id in the structure if it is a digit. I also don't know if I'm calling it right in main and I need to pass in the whole records table and I think that is causing the error but I don't know. Any help would be appreciated.

I also understand that the is digit returns 1 for true and 0 for false but what to do with it after that I guess? I'm trying to explain this as best as I can! Thanks for the help so far!

#include <ctype.h>
#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <stdio.h>

struct customers
{
	int cust_id;
	char cust_name[20];
	static char states [50][3];
	char discount;
	double balance_due;
	int order_out;
};
struct myRecords
{
	customers rec[20];
};

using namespace std;

int is_int(char prompt[50]);

int main()
{
	int cust_id;
	myRecords table, *point_table;
	point_table = &table;

	cust_id = is_int("Please enter a customer id: ");

}//end of main

/**************************************
*Function to test if it is an integer *
**************************************/
int is_int(char prompt[50], struct myRecords* table)
{
	int y = 0;
	int i;
	int len = strlen(prompt);
	for (i=0; prompt[i]; i++)
	{
		if (!isdigit(prompt[i]))
			return 0;
		else
			return 1;
	}
}