C Programming Questions and Answers – Standard Input & Output – 2

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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.

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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?

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  1.     #include <stdio.h>
  2.     int main()
  3.     {
  4.         char c = '�';
  5.         putchar(c);
  6.     }

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

Answer: b
Explanation: None.
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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)?

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  1.     gcc -otest test.c
  2.     ./test < myfile
  3.  
  4.     #include <stdio.h>
  5.     int main()
  6.     {
  7.         char c = 'd';
  8.         putchar(c);
  9.     }

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

  1.     gcc -otest test.c
  2.     ./test > myfile
  3.  
  4.      #include <stdio.h>
  5.     int main(int argc, char **argv)
  6.     {
  7.         char c = 'd';
  8.         putchar(c);
  9.         printf(" %d\n", argc);
  10.     }

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?

  1.     gcc -o test test.c
  2.     ./test > myfile
  3.  
  4.     #include <stdio.h>
  5.     int main(int argc, char **argv)
  6.     {
  7.         char c = 'd';
  8.         putchar(c);
  9.         printf(" %d\n", argc);
  10.     }

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.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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