Output of C programs | Set 40 (File handling)
Prerequisite : File handling
1. What is the output of this program by manipulating the text file?
#include <stdio.h>
int main()
{
if ( remove ( "myfile.txt" ) != 0)
perror ( "Error" );
else
puts ( "Success" );
return 0;
}
|
Options:
a) Error
b) Success
c) Runtime Error
d) Can’t say
Answer : d
Explanation : If myfile.txt exists, then it will delete the file. Else it will print an error message.
2. What is the output of this program?
#include <stdio.h>
int main()
{
FILE * p;
int c;
int n = 0;
p = fopen ( "myfile.txt" , "r" );
if (p == NULL)
perror ( "Error opening file" );
else {
do {
c = getc (p);
if (c == '$' )
n++;
} while (c != EOF);
fclose (p);
printf ( "%d\n" , n);
}
return 0;
}
|
Options:
a) Count of ‘$’ symbol
b) Error opening file
c) Any of the mentioned
d) None of the mentioned
Answer : c
Explanation : Any one is possible – Either the file doesn’t exist or If exist, it will print the total number of ‘$’ character.
3. What is the output of this program in the text file?
#include <stdio.h>
int main()
{
FILE * pFile;
char c;
pFile = fopen ( "sample.txt" , "wt" );
for (c = 'A' ; c <= 'E' ; c++) {
putc (c, pFile);
}
fclose (pFile);
return 0;
}
|
Options:
a) ABCD
b) ABC
c) ABCDE
d) None of the mentioned
Answer : c
Explanation : In this program, We are printing from A to E by using the putc function.
Output:
$ g++ out2.cpp
$ a.out
ABCDE
4. What is the name of the myfile2 file after executing this program?
#include <stdio.h>
int main()
{
int result;
char oldname[] = "myfile2.txt" ;
char newname[] = "newname.txt" ;
result = rename (oldname, newname);
if (result == 0)
puts ( "success" );
else
perror ( "Error" );
return 0;
}
|
Options:
a) name
b) new
c) newname
d) None of the mentioned
Answer : c
Explanation : In this program, We are renaming the myfile2 to newname by using the function rename.
Output:
myfile2.txt is renamed to newname.txt
5. How many number of characters are available in newname.txt?
#include <stdio.h>
int main()
{
FILE * p;
int n = 0;
p = fopen ( "newname.txt" , "rb" );
if (p == NULL)
perror ( "Error opening file" );
else {
while ( fgetc (p) != EOF) {
++n;
}
if ( feof (p)) {
printf ( "%d\n" , n);
} else
puts ( "End-of-File was not reached." );
fclose (p);
}
return 0;
}
|
Options:
a) 10
b) 15
c) Depends on the text file
d) None of the mentioned
Answer : c
Explanation : In this program, We are reading the number of characters in the program by using the function feof.
Output:
$ g++ out4.cpp
$ a.out
162
Related Article : Quiz on File Handling
Last Updated :
18 Aug, 2017
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