C Input & Output Questions and Answers

This set of C Multiple Choice Questions & Answers (MCQs) focuses on “Standard Input & Output – 2”.

Pre-requisite for this C MCQ set: Advanced C Programming Video Tutorial.

1. Which is true about function tolower?
a) The function tolower is defined in <ctype.h>
b) Converts an uppercase letter to lowercase
c) Returns other characters untouched
d) None of the mentioned
View Answer

Answer: d
Explanation: None.

2. What will be the output of the following C code?

Sanfoundry Certification Contest of the Month is Live. 100+ Subjects. Participate Now!

```
    #include <stdio.h>
```
```
    int main()
```
```
    {
```
```
        char c = '�';
```
```
        putchar(c);
```
```
    }
```

a) Compile time error
b) Nothing
c) 0
d) Undefined behaviour
View Answer

Answer: b
Explanation: None.

Check this: Computer Science MCQs | Computer Science Books

3. putchar(c) function/macro always outputs character c to the __________
a) screen
b) standard output
c) depends on the compiler
d) depends on the standard
View Answer

Answer: b
Explanation: None.

4. What will be the output of the following C code if following commands are used to run (considering myfile exists)?

```
    gcc -otest test.c
```
```
    ./test < myfile
```
```
 
```
```
    #include <stdio.h>
```
```
    int main()
```
```
    {
```
```
        char c = 'd';
```
```
        putchar(c);
```
```
    }
```

a) Compile time error (after first command)
b) d in the myfile file
c) d on the screen
d) Undefined behaviour
View Answer

Answer: c
Explanation: None.

5. What will be the output of the following C code if following commands are used to run (considering myfile exists)?

```
    gcc -otest test.c
```
```
    ./test > myfile
```
```
 
```
```
     #include <stdio.h>
```
```
    int main(int argc, char **argv)
```
```
    {
```
```
        char c = 'd';
```
```
        putchar(c);
```
```
        printf(" %d\n", argc);
```
```
    }
```

a) d 2 in myfile
b) d 1 in myfile
c) d in myfile and 1 in screen
d) d in myfile and 2 in screen
View Answer

Answer: b
Explanation: None.

6. What will be the output of the following C code if following commands are used to run and if myfile does not exist?

```
    gcc -o test test.c
```
```
    ./test > myfile
```
```
 
```
```
    #include <stdio.h>
```
```
    int main(int argc, char **argv)
```
```
    {
```
```
        char c = 'd';
```
```
        putchar(c);
```
```
        printf(" %d\n", argc);
```
```
    }
```

a) d 2 in myfile
b) d 1 in myfile
c) Depends on the system
d) Depends on the standard
View Answer

Answer: b
Explanation: None.

7. The statement prog < infile causes _________
a) prog to read characters from infile
b) prog to write characters to infile
c) infile to read characters from prog instead
d) nothing
View Answer

Answer: a
Explanation: None.

Sanfoundry Global Education & Learning Series – C Programming Language.

To practice all areas of C language, here is complete set of 1000+ Multiple Choice Questions and Answers.

« Prev - C Programming Questions and Answers – Standard Input & Output – 1

» Next - C Programming Questions and Answers – Formatted Output – 1

Next Steps: