//function prototype
#include<stdio.h>
#include<stdlib.h>
int isprime(int);
int ismax(int ,int *);
void isoddeven(int);

int main()
{
	int *p,n,i,max,mf;
	printf("Enter the size of the array :");
	scanf("%d",&n);
	p=(int*)malloc(sizeof(int)*n); //dynamic size allocation
	printf("Enter the nos. : ");
	for(i=0;i<n;i++)
		scanf("%d",(p+i)); //get the nos from the user
	mf=*(p+1); //declaring the no. in prime loc. 2, as largest number
	printf("\nNos. in the prime locations are :-");
	for(i=0;i<n;i++)
		if(isprime(i+1)) //checks whether the loc. is prime or not
		{
			printf("\n%d (location %d) ",*(p+i),(i+1));
			isoddeven(*(p+i)); //prints Odd or Even
			max=ismax(*(p+i),&mf); //call by reference
					       //check for the max number
		}
	printf("\n\nLargest no.among the nos.in prime locations : %d",max);
}
//function definations
int isprime(int x)
{
	int i;
	if(x==1)
		return 0; //not a prime no.
	else
		for(i=2;i<x;i++)
		{
			if(x%i==0)
			{
				return 0; //not a prime no.
				break;
			}
			else
				return 1; //prime no.
		}
}
void isoddeven(int y)
{
	if(y==0)
		printf("is neither EVEN nor ODD");
	else if(y%2==0)
		printf("is an EVEN number");
	else
		printf("is an ODD number");
}
int ismax(int z,int *m) //call by reference
{
	if(z>(*m))
	{
		(*m)=z;
		return z;
	}
	else
		return *m;
}
by

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About C

C language is one of the most popular general-purpose programming language developed by Dennis Ritchie at Bell laboratories for UNIX operating system. The initial release of C Language was in the year 1972. Most of the desktop operating systems are written in C Language.

Key features:

  • Structured Programming
  • Popular system programming language
  • UNIX, MySQL and Oracle are completely written in C.
  • Supports variety of platforms
  • Efficient and also handle low-level activities.
  • As fast as assembly language and hence used as system development language.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition if-else is used.

if(conditional-expression) {
   // code
} else {
   // code
}

You can also use if-else for nested Ifs and if-else-if ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to if-else-if ladder.

switch(conditional-expression) {    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
...    
    
default:     
 // code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  // code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while(condition) {  
 // code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {
  // code 
} while (condition);

Arrays

Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.

Syntax

One dimentional Array:

data-type array-name[size];

Two dimensional array:

data-type array-name[size][size];

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity.

Two types of functions are present in C

  1. Library Functions:

Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,

  1. User defined functions:

User defined functions are the ones which are written by the programmer based on the requirement.

How to declare a Function

return_type function_name(parameters);

How to call a Function

function_name (parameters)

How to define a Function

return_type function_name(parameters) {  
  //code
}