Important features and of C programming language

1. Function prototype declaration. Like declaring a variable in java, you can also declare a function. It is useful if you are going to call the function before the definition of the function. 
2. C has pointer operator.

	#include <stdio.h>
	int main(){
	int a = 15;
	int *p; // holds the value of a
	// pointer can also be declared like int* p; (some people prefer this style)
	p = &a; // we assign the address of a to p
	// we can also make it in one line like this: int *p = &a;
	printf("%d\n", &a); // will return the address of a
	printf("%d\n", *p); // will return the value of a (15)
	printf("%d\n", a); // will return the value of a (15)
	printf("%d\n", p); // will return the address of a
	printf("%d\n", &p); // will return the address of p
	return 0;
	}

view raw pointer.c hosted with ❤ by GitHub
3. C doesn't have a string data type. Instead we can use char array. 
4. Structure is a custom data type. It's kind of an "object".

	#include <stdio.h>
	int main() {
	//Declaration
	struct student{
	// string muss be terminated by ['\0']
	char name[20];
	int roll;
	int age;
	};
	//create struct variable
	struct student s1 = {"Bob", 3, 15};
	//or you can also do
	struct student s2;
	printf("Enter your name\n");
	scanf("%s",s2.name);
	printf("Enter your roll\n");
	scanf("%d",&s2.roll);
	printf("Enter your age\n");
	scanf("%d",&s2.age);
	//Accessing struct variable
	printf("Name: %s\n",s1.name);
	return 0;
	} // example taken from youtube channel We the computer guys

view raw struct.c hosted with ❤ by GitHub
5. "%lf" to format double
6. "%.2f" to format float with 2 digit after a comma. 
7. "%d" to format an integer. 
8.  Store only positiv integer value: unsigned int a;
9. int A[4], printf("%d\n", A); will return the base address (Address of first element)
10. int A[4]; A[0] = 3;  printf("%d\n", A*); will return the value of the first element.
11. Casting an Array to a pointer, now you can access the element without brackets

	int main() {
	int myArray [10];
	int i,j;
	for ( i = 0; i < 10; i++ ) {
	*(myArray + i) = i + 1; /* set element at location i to i+1 */
	}
	int n = sizeof(myArray)/sizeof(myArray[0]);
	printf("%d\n\n",n);
	/* output each array element's value */
	for (j = n; j > 0; j-- ) {
	printf("Element[%d] = %d\n", j, *(myArray+j-1) );
	}
	return 0;
	}

view raw arrays_ex.c hosted with ❤ by GitHub