What is dangling pointer in C?

Uninitialized pointers are called as wild pointers in C which points to arbitrary (random) memory location. This wild pointer may lead a program to behave wrongly or to crash.

• File pointer is a pointer which is used to handle and keep track on the files being accessed. A new data type called “FILE” is used to declare file pointer. This data type is defined in stdio.h file. File pointer is declared as FILE *fp. Where, ‘fp’ is a file pointer.
• fopen() function is used to open a file that returns a FILE pointer. Once file is opened, file pointer can be used to perform I/O operations on the file. fclose() function is used to close the file.

In C, a file pointer is a variable that is used to point to a specific location within a file. It is used to read from or write to a file. The stdio.h library provides functions for file I/O operations, and the FILE type is used to define a file pointer.

Here is an example that demonstrates the use of a file pointer to read and write to a file:

#include <stdio.h>

int main() {
   FILE *fp;
   char buffer[100];

   // Open file for writing
   fp = fopen("test.txt", "w");
   fprintf(fp, "This is written to the file.\n");
   fclose(fp);

   // Open file for reading
   fp = fopen("test.txt", "r");
   fscanf(fp, "%s", buffer);
   printf("Contents of file: %s\n", buffer);
   fclose(fp);

   return 0;
}

In this example, a file pointer named fp is declared as a FILE type. The fopen() function is used to open the file named "test.txt" in write mode with the w mode argument. The fprintf() function is used to write a string to the file, and the fclose() function is used to close the file.

Next, the file is opened again using fopen() in read mode with the r mode argument. The fscanf() function is used to read the contents of the file into the buffer array. Finally, the contents of the buffer array are printed to the console using printf(), and the file is closed again using fclose().

When this program is run, it will write the string "This is written to the file." to the "test.txt" file, and then read the contents of the file and print them to the console.

Void pointer is a generic pointer that can be used to point another variable of any data type. Null pointer is a pointer which is pointing to nothing.

Const pointer is a pointer that can’t change the address of the variable that is pointing to.
Once const pointer is made to point one variable, we can’t change this pointer to point to any other variable. This pointer is called const pointer.

C language was developed in 1972 at bell laboratories of AT&T.

C, computer programming language developed in the early 1970s by American computer scientist Dennis M. Ritchie at Bell Laboratories (formerly AT&T Bell Laboratories). C was designed as a minimalist language to be used in writing operating systems for minicomputers, such as the DEC PDP 7, which had very limited memories compared with the mainframe computers of the period. The language was devised during 1969

printf(): The printf() function is used to print the integer, character, float and string values on to the screen.

Following are the format specifier:

• %d: It is a format specifier used to print an integer value.
• %s: It is a format specifier used to print a string.
• %c: It is a format specifier used to display a character value.
• %f: It is a format specifier used to display a floating point value.

scanf(): The scanf() function is used to take input from the user.