C Programming - File I/O

Computer Science

Software Engineering

ISO/IEC 9899

ANSI C

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| By Mr_chan

Mr_chan

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Quizzes Created: 1 | Total Attempts: 702

| Attempts: 702 | Questions: 12

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1. The following C code reads from your keyboard (use getchar()) and writes to a file (use fputc() function) named "myfile.txt":

_A_                                //preprocessor declaration
main()
{
char ch;
_B_                               //declare the file pointer as: fp

_C_                               //open the file for writing
if (fp==_D_){                         //get into the "printf" statement if the file cannot be opened
    printf("Cannot open the file!\n");
    exit(1);
}

ch = getchar();                        //get a character from keyboard
while ( _E_ ){                      //continue processing the input if &ltENTER> is not pressed
    _F_                             // write 1 character to the file
    _G_                                    // get the next character from keyboard
}

_H_                                 // close the file
}

What would be _D_ ?

In the given code, _D_ is the file pointer "fp". It is used to open the file for writing. If the file cannot be opened, the condition "fp==NULL" will be true, indicating that the file pointer is pointing to nothing, and the program will enter the "printf" statement to display the message "Cannot open the file!". Therefore, the correct answer for _D_ is NULL.

Explanation

Submit

About This Quiz

*Please be reminded: when you answer the fill-in-the-blanks questions, do not use excessive/redundant -blanks- ,e. G.
enter:- if(a>b) ,
not if(a > b)
Good luck !

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2. The following C code reads from your keyboard (use getchar()) and writes to a file (use fputc() function) named "myfile.txt":

_A_                                //preprocessor declaration
main()
{
char ch;
_B_                               //declare the file pointer as: fp

_C_                               //open the file for writing
if (fp=_D_){                         //get into the "printf" statement if the file cannot be opened
    printf("Cannot open the file!\n");
    exit(1);
}

ch = getchar();                        //get a character from keyboard
while ( _E_ ){                      //continue processing the input if &ltENTER> is not pressed
    _F_                             // write 1 character to the file
    _G_                                    // get the next character from keyboard
}

_H_                                 // close the file
}

What would be _H_ ?

The correct answer for _H_ would be "fclose(fp)". This is because the code is closing the file that was opened for writing using the fopen function. The fclose function is used to close the file and release any resources associated with it.

Explanation

Submit

3. The following C code reads from your keyboard (use getchar()) and writes to a file (use fputc() function) named "myfile.txt":

_A_                                //preprocessor declaration
main()
{
char ch;
_B_                               //declare the file pointer as: fp

_C_                               //open the file for writing
if (fp==_D_){                         //get into the "printf" statement if the file cannot be opened
    printf("Cannot open the file!\n");
    exit(1);
}

ch = getchar();                        //get a character from keyboard
while ( _E_ ){                      //continue processing the input if &ltENTER> is not pressed
    _F_                             // write 1 character to the file
    _G_                                    // get the next character from keyboard
}

_H_                                 // close the file
}

What would be _B_ ?

The variable declaration in C code is done by specifying the data type followed by the variable name. In this case, the variable name is "fp" and the data type is "FILE *", which indicates that "fp" is a pointer to a FILE type. Therefore, the correct answer for _B_ is "FILE *fp;".

Explanation

Submit

4. The code below read from your keyboard input until an ENTER is pressed, convert any lower case letter to upper case, and then write it to a file:

L1: ch=getchar();
L2: while (ch!='\n') {
L3:    if (ch>='a' and ch<='z')
L4:    ch=ch-'A'+'a';
L5:    fputc(ch,fp);
L6:    ch=getchar();
L7: }
L8: fclose(fp);

Which line(s) is/are incorrect ?

L3,L4

L3,L4,L5

L3,L4,L7

L3,L4,L5,L7

L2,L3,L4,L5,L7

L3: Use '&&' instead of 'and' for C conditional statement.
L4 should be ch=ch-'a'+'A';
L7: ';' after a loop is optional

Explanation

L3: Use '&&' instead of 'and' for C conditional statement.
L4 should be ch=ch-'a'+'A';
L7: ';' after a loop is optional

Submit

5. The following C code reads from your keyboard (use getchar()) and writes to a file (use fputc() function) named "myfile.txt":

_A_                                //preprocessor declaration
main()
{
char ch;
_B_                               //declare the file pointer as: fp

_C_                               //open the file for writing
if (fp=_D_){                         //get into the "printf" statement if &ltENTER> the file cannot be opened
    printf("Cannot open the file!\n");
    exit(1);
}

ch = getchar();                        //get a character from keyboard
while ( _E_ ){                      //continue processing the input if is not pressed
    _F_                             // write 1 character to the file
    _G_                                    // get the next character from keyboard
}

_H_                                 // close the file
}

What would be _F_ ?

The correct answer for _F_ would be "fputc(ch,fp)". This is because the fputc() function is used to write a character to the file specified by the file pointer "fp". In this code, it is used to write the character "ch" to the file.

Explanation

Submit

6.
A file (name.txt) containing a list of your classmates reads as below (ALL names follow immediately with a 'new line' character):

What would be the output to the screen on running the code below:

#include <stdio.h>
main()
{
char str1[20] = "Hello, boys";
char str2[100] = "God created the world in 7 days.";
FILE *fp;

fp=fopen("name.txt","r");

if (fp==NULL){
printf("Cant open !\n");
exit(1);
}

fgets(str1,12,fp);
fgets(&str2[12],10,fp);

printf("%s",str2);

fclose(fp);
}

God created Ella

God createdElla

God created Hebe

God createdHebe

God created Hebeworld in 7 days.

The fgets function reads at most one less than the number of characters specified by size from the given stream and stores them in the string str. Reading stops when a newline character is found, at end-of-file or error. The newline, if any, is retained. If any characters are read and there is no error, a '\0' character is appended to end the string.

Explanation

Submit

7. The correct code of previous question:

L1: ch=getchar();
L2: while (ch!='\n') {
L3:    if (ch>='a' && ch<='z')
L4:    ch=ch-'a'+'A';
L5:    fputc(ch,fp);
L6:    ch=getchar();
L7: }
L8: fclose(fp);

Right after execution of L8, a special character would be written automatically to the file (i.e. fp). (a) What is the character ?   (b) What is the purpose of L8 ?

(a)'\n' (b)release the resources occupied by the program during file access, e.g. memory

(a)'\0' (b)release the resources occupied by the program during file access, e.g. memory

(a)EOF (b)release the resources occupied by the program during file access, e.g. disk storage

(a)'\0' (b)release the resources occupied by the program during file access, e.g. disk storage

(a)EOF (b)release the resources occupied by the program during file access, e.g. memory

(a) End-of-File
(b) when a file is opened: file data from disk storage is -copied- to the RAM(memory). Memory is important resource for efficient running of the computer.

Explanation

(a) End-of-File
(b) when a file is opened: file data from disk storage is -copied- to the RAM(memory). Memory is important resource for efficient running of the computer.

Submit

8. The following C code reads from your keyboard (use getchar()) and writes to a file (use fputc() function) named "myfile.txt":

_A_                                //preprocessor declaration
main()
{
char ch;
_B_                               //declare the file pointer as: fp

_C_                               //open the file for writing
if (fp=_D_){                         //get into the "printf" statement if the file cannot be opened
    printf("Cannot open the file!\n");
    exit(1);
}

ch = getchar();                        //get a character from keyboard
while ( _E_ ){                      //continue processing the input if &ltENTER> is not pressed
    _F_                             // write 1 character to the file
    _G_                                    // get the next character from keyboard
}

_H_                                 // close the file
}

What would be _G_ ?

The correct answer for _G_ would be "fputc(ch, fp)". This is because the code is using the fputc() function to write one character (stored in the variable ch) to the file pointed by the file pointer fp.

Explanation

Submit

9. The following C code reads from your keyboard (use getchar()) and writes to a file (use fputc() function) named "myfile.txt":

_A_                                //preprocessor declaration
main()
{
char ch;
_B_                               //declare the file pointer as: fp

_C_                               //open the file for writing
if (fp==_D_){                         //get into the "printf" statement if the file cannot be opened
    printf("Cannot open the file!\n");
    exit(1);
}

ch = getchar();                        //get a character from keyboard
while ( _E_ ){                      //continue processing the input if &ltENTER> is not pressed
    _F_                             // write 1 character to the file
    _G_                                    // get the next character from keyboard
}

_H_                                 // close the file
}

What would be _C_ ?

_C_ would be "fp=fopen("myfile.txt","w");". This line of code opens the file named "myfile.txt" in write mode and assigns the file pointer to the variable "fp".

Explanation

_C_ would be "fp=fopen("myfile.txt","w");". This line of code opens the file named "myfile.txt" in write mode and assigns the file pointer to the variable "fp".

Submit

10. The following C code reads from your keyboard (use getchar()) and writes to a file (use fputc() function) named "myfile.txt":

_A_                                //preprocessor declaration
main()
{
char ch;
_B_                               //declare the file pointer as: fp

_C_                               //open the file for writing
if (fp=_D_){                         //get into the "printf" statement if &ltENTER> the file cannot be opened
    printf("Cannot open the file!\n");
    exit(1);
}

ch = getchar();                        //get a character from keyboard
while ( _E_ ){                      //continue processing the input if is not pressed
    _F_                             // write 1 character to the file
    _G_                                    // get the next character from keyboard
}

_H_                                 // close the file
}

What would be _E_ ?

The condition for _E_ would be "ch!='\n'", which means that while the character read from the keyboard is not equal to a newline character, the loop will continue processing the input.

Explanation

The condition for _E_ would be "ch!='\n'", which means that while the character read from the keyboard is not equal to a newline character, the loop will continue processing the input.

Submit

11. The following C code reads from your keyboard (use getchar()) and writes to a file (use fputc() function) named "myfile.txt":

_A_                                //preprocessor declaration
main()
{
char ch;
_B_                               //declare the file pointer as: fp

_C_                               //open the file for writing
if (fp==_D_){                         //get into the "printf" statement if the file cannot be opened
    printf("Cannot open the file!\n");
    exit(1);
}

ch = getchar();                        //get a character from keyboard
while ( _E_ ){                      //continue processing the input if is &ltENTER> not pressed
    _F_                             // write 1 character to the file
    _G_                                    // get the next character from keyboard
}

_H_                                 // close the file
}

What would be _A_ ?

not-available-via-ai

Explanation

not-available-via-ai

Submit

12. The text file "MLKing.txt" consists of the following text:

Determine the output when the following is executed:

#include &ltstdio.h>
main()
{
int i;
char c;
FILE *fptr;

fptr=fopen("MLKing.txt","r");

for(i=0; i<15; i++)
{
    c=fgetc(fptr);
    if (i>7)
      putchar(c);
}

fclose(fptr);
}

Ace is n

Ce is no

Ace is

Ce is n

Ce is

1) at the start of text, i=0
2) the output should be from i=8 to i=14

Explanation

1) at the start of text, i=0
2) the output should be from i=8 to i=14

Submit

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