# Thread: Help with C- simple qns

1. ## Help with C- simple qns

Hi all

i just wanted to kno how to multiply every second digit by 2 or 3?

and then check if its in increasing order

so its:
//first scan the user input

num[i]= n;

/* now how to multiply the 2nd by 2 ? */

checking if its order:

if(num[i] > num[i+1]){
etc....

also is there any website that shows how to read a file and search the file WITHOUT USING THE STRING.H LIBRARY?

thanks

2. Imagine a for loop (for instance), with one number being incremented by two, every loop:

number += 2;

You'll have to use some logic to decide when the program should multiply by two, and when it should multiply by 3.

Are you familiar with the C modulus operator (%). It's very handy for logic like this, but I can't tell from your code, just what you want, yet.

Work on it by hand a bit (paper and pencil), and re-post your newer attempt, when it's ready. The more specific your question, the more helpful we can be.

3. hi

i understand what u mean...

and here is my complete code
Code:
```//reading the integers

printf("Enter 10 integers:\n");
for (i=0; i < 10; i=i+1) {
scanf("%d", &n);
num[i]=n;
}```
now here i am getting the nos by the user- which works ok, but now i want to multiply every second by 2. How can i do that? and then after multiplying it i want to see if its in order:
Code:
``` int order(int nos[], int lenth) {
int i, retval=0, temp;

for (i=0; (i < lenth-1) && (retval == 0); i=i+1) {
//checks the ints and sorts them
if (nos[i] > nos[i+1]) {
temp=nos[i];
nos[i]=nos[i+1];
nos[i+1]=temp;```
so i dont kno how to x the 2nd digit by 2

also i dont know how to search for a string/array without using the string.h library?

thank u very much

4. Originally Posted by papermate
hi

i understand what u mean...

and here is my complete code
Code:
```//reading the integers

printf("Enter 10 integers:\n");
for (i=0; i < 10; i=i+1) {
scanf("%d", &n);
num[i]=n;
}```
now here i am getting the nos by the user- which works ok, but now i want to multiply every second by 2. How can i do that? and then after multiplying it i want to see if its in order:
Code:
``` int order(int nos[], int lenth) {
int i, retval=0, temp;

for (i=0; (i < lenth-1) && (retval == 0); i=i+1) {
//checks the ints and sorts them
if (nos[i] > nos[i+1]) {
temp=nos[i];
nos[i]=nos[i+1];
nos[i+1]=temp;```
so i dont kno how to x the 2nd digit by 2

also i dont know how to search for a string/array without using the string.h library?

thank u very much
Doing something with every second number in this case, might mean using the modulus operator: %

Code:
```if(num % 2 == 0)
//do something, num is an even number```
num could be an index number for your nos array. I'm unclear what "length" is in your code. For sorting I'd use a simple Selection sort:

Code:
```for(i = 0; i < NumberOfNumbers -1; i++) {
for(j = i+1; j < NumberOfNumbers; j++) {
if(array[i] > array[j]) {
temp = array[i];
array[i] = array[j];
array[j] = temp;
}
}
}```
I'd suggest also putting a getchar() right after your scanf()'s. Here, it stops the very annoying problem of the user puts in a letter, instead of a number, and now the program loops straight up to 10 inputs, all garbage.

Other times a getchar() after a scanf() will save the day (especially true for char inputs in a program).

5. ## Here is the first part!!!

Here is the first part!!!

Code:
```#include<stdio.h>
#include<conio.h>
void main()
{
int n,m,o,num[20],i=0,j;
scanf("%d",&n);
m=n;
o=n;
while(o>0)
{
o=o/10;
num[i++]=o%10;
o=o/10;
}
for(j=0;j<=i-1;j++)
printf("%d\t",num[j]*2);
getch();
}```

6. ## Probably this is what u want!!!

Finalized!!!
Code:
```// 2nddidit.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include<stdio.h>
#include<conio.h>
int chkasc(int num[],int n);
void main()
{
int n,m,o,num[20],i=0,j;
scanf("%d",&n);
m=n;
o=n;
while(o>0)
{
o=o/10;
num[i++]=o%10;
o=o/10;
}
for(j=0;j<=i-1;j++)
printf("%d\t",num[j]*2);
if(chkasc(num,i-2)==0)
printf("The values are in ascending order");
else
printf("The values are not in ascending order");
getch();
}
int chkasc(int num[],int n)
{
int hold=-999,i;
for(i=0;i<=n;i++)
{
if(num[i]>hold)
{
hold=num[i];
continue;
}
else
{
return 1;
}
}
return 0;
}```

7. Hi

thanks a lot for ur help!!!!

Also i am not sure how to search without using the string functions....

this is what i have so far:
Code:
```void search(char text[][MAX_LEN+1], char rep[]);

if(argc>2) {
c= getchar();```
again, thanks for ur help