The ungetc() function pushes the character c back onto the named input stream, which must be open for reading.

This character will be returned on the next call to getc or fread for that stream.

One character can be pushed back in all situations.

A second call to ungetc without a call to getc will force the previous character to be forgotten.

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

Function atoi() converts the string to integer.
Function atof() converts the string to float.

result1 = result1+atoi(i);
Here result1 = 10 + atoi(55.555);
result1 = 10 + 55;
result1 = 65;

result2 = result2+atof(i);
Here result2 = 11.111 + atof(55.555);
result2 = 11.111 + 55.555000;
result2 = 66.666000;
So the output is "65, 66.666000" .

"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.

memcmp compares the first 2 bytes of the blocks dest and src as unsigned chars. So, the ASCII value of 97 is 'a'.

if((i = memcmp(dest, src, 2))==0) When comparing the array dest and src as unsigned chars, the first 2 bytes are same in both variables.so memcmp returns '0'.
Then, the if(0=0) condition is satisfied. Hence the output is "Got it".

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

The gcvt() function converts a floating-point number to a string. It converts given value to a null-terminated string.

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

int main(void)
{
	char str[25];
	double num;
	int sig = 5; /* significant digits */

	/* a regular number */
	num = 9.876;
	gcvt(num, sig, str);
	printf("string = %s\n", str);

	/* a negative number */
	num = -123.4567;
	gcvt(num, sig, str);
	printf("string = %s\n", str);

	/* scientific notation */
	num = 0.678e5;
	gcvt(num, sig, str);
	printf("string = %s\n", str);

	return(0);
}

Output:
string = 9.876
string = -123.46
string = 67800

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;
}

for(i=1; i<=5; i++) Here the for loop runs 5 times.

Loop 1:
scanf("%c", &c); Here we give 'a' as input.
printf("%c", c); prints the character 'a' which is given in the previous "scanf()" statement.
ungetc(c, stdin); "ungetc()" function pushes character 'a' back into input stream.

Loop 2:
Here the scanf("%c", &c); get the input from "stdin" because of "ungetc" function.
printf("%c", c); Now variable c = 'a'. So it prints the character 'a'.
ungetc(c, stdin); "ungetc()" function pushes character 'a' back into input stream.

This above process will be repeated in Loop 3, Loop 4, Loop 5.