What is stderr?

Do like this fprintf(stdout, "%s %d %f", str, i, a);

stdio.h, which stands for "standard input/output header", is the header in the C standard library that contains macro definitions, constants, and declarations of functions and types used for various standard input and output operations.

strrchr() returns a pointer to the last occurrence of character in a string.

Example:

#include <stdio.h>
#include <string.h>

int main()
{
    char str[30] = "12345678910111213";
    printf("The last position of '2' is %d.\n",
            strrchr(str, '2') - str);
    return 0;
}

Output: The last position of '2' is 14.

rewind() takes the file pointer to the beginning of the file. so that the next I/O operation will take place at the beginning of the file.
Example: rewind(FilePointer);

Step 1: const c = -11; The constant variable 'c' is declared and initialized to value "-11".

Step 2: const int d = 34; The constant variable 'd' is declared as an integer and initialized to value '34'.

Step 3: printf("%d, %d\n", c, d); The value of the variable 'c' and 'd' are printed.

Hence the output of the program is -11, 34

"fflush()" flush any buffered output associated with filename, which is either a file opened for writing or a shell command for redirecting output to a pipe or coprocess.
Example:
fflush(FilePointer);
fflush(NULL); flushes all streams.

The randomize() function initializes the random number generator with a random value based on time. You can try the sample program given below in Turbo-C, it may not work as expected in other compilers.

/* Prints a random number in the range 0 to 99 */

#include <stdlib.h>
#include <stdio.h>
#include <time.h>

int main(void)
{
    randomize();
    printf("Random number in the 0-99 range: %d\n", random (100));
    return 0;
}

1. itoa() converts an integer to a string.
2. ltoa() converts a long to a string.
3. ultoa() converts an unsigned long to a string.
4. sprintf() sends formatted output to a string, so it can be used to convert any type of values to string type.

#include<stdio.h>
#include<stdlib.h>

int main(void)
{
   int   num1 = 12345;
   float num2 = 5.12;
   char str1[20];
   char str2[20];

   itoa(num1, str1, 10); /* 10 radix value */
   printf("integer = %d string = %s \n", num1, str1);

   sprintf(str2, "%f", num2);
   printf("float = %f string = %s", num2, str2);

   return 0;
}

// Output:
// integer = 12345 string = 12345
// float = 5.120000 string = 5.120000

Given 3.14 is a double constant.

To specify 3.14 as long double, we have to add L to the 3.14. (i.e 3.14L)