Working with pointer

What is pointer?

A pointer is a memory address(virtual) which is actually a integer that carry the location.

What is location?

Let define an integer variable in c int a = 10;. After defining a variable program will stored this variable in memory and remember the memory address so that whenever program need this variable 'a' program can access the value of this variable by looking on this memory address. This address is the location of the variable in the memory. This location is a integer number which indicate location. To access this location of the variable use '&' sign before the variable name.

    printf("%d\n", a); // return  the value of a 
    printf("%d\n", &a); // return the address of a

What will happen when a variable doesn't initialized with a value? Then the return value of the variable will be a garbage value if it is a local variable, if the variable declared as global then initially C assign 0. But the location is created after declare a variable.

Remember when C program take input from user from console it use a function scanf(...) and for output on console use printf(...)

    int x;
    scanf("%d", &x);
    printf("%d", x);

why scanf use '&' sign before the variable name? This indicate that take the value and store it in &x location.

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To define a pointer use '*' simple before the variable name.

    int *int_point1; // define a pointer of an integer
    float *float_point1; // define a pointer of an float
    char *char_point1; // define a pointer of an character

How to copy assign location for a defined pointer

&variable_name return the location of this variable; so assign this to another pointer. To access the value of a pointer use * before the pointer name. To access the location just use the variable name.

    int int_var1 = 10; // define an integer
    float float_var1 = 98.23423; // define a floating
    char char_var1 = 'U'; // define a character

    int *int_point1; // define a pointer of an integer
    float *float_point1; // define a pointer of an float
    char *char_point1; // define a pointer of an character


    /// assign the location of particular pointer
    int_point1 = &int_var1;
    float_point1 = &float_var1;
    char_point1 = &char_var1;

    printf("Integer memory: %d, value: %d \n",int_point1,*int_point1);
    printf("Float memory: %d, value: %.2f \n",float_point1,*float_point1);
    printf("Character memory: %d, value: %c \n",char_point1,*char_point1);

If a pointer locate a variable location then what is the location of the pointer itself? To access the location of a pointer itself simply use& sign before the pointer name. So in briefly for a pointer p value of the pointer *p, location of the pointer itself &p and the location the pointer point is p. On the other hand for a variable v value of the variable is v and address of the variable is &v.

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A simple C code about pointer