C Programming Multiple Choice Question - Printf & Scanf
This section focuses on the "Printf And Scanf" of the C programming. These Multiple Choice Questions (mcq) should be practiced to improve the C programming skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
1. What is the output of this program?
#include <stdio.h>
int main()
{
printf("variable! %d", x);
return 0;
}
A. variable! x
B. variable! followed by a junk value
C. Compile time error
D. variable!
View Answer
Ans : C
Explanation: It will give compile time error since x is not declared.
2. What is the output of this program?
#include <stdio.h>
int main()
{
int main = 3;
printf("%d", main);
return 0;
}
A. 3
B. Compile time error
C. Run time error
D. give garbage value
View Answer
Ans : A
Explanation: A C program can have same function name and same variable name.
3. What is the output of this program? if input a is 1 and b is 2
#include <stdio.h>
int main()
{
int a, b;
printf("%d", scanf("%d %d",&a,&b));
return 0;
}
A. 1
B. 2
C. runtime error
D. compile time error
View Answer
Ans : B
Explanation: In C, scanf returns the number of inputs it has successfully read.
4. What is the output of this program?
#include <stdio.h>
void main()
{
printf("hello\rworld\n");
printf("hello\b\b\bworld\n");
}
A. hello
helloworld
B. world
heworld
C. helloworld
hellold
D. None of the mentioned
View Answer
Ans : B
Explanation: "" for a backspace, means if u print it, cursor will print and come back 1 character . '
' is used for carriage return to come 1 line back or in start of line.
5. What is the output of this program?
#include <stdio.h>
int main()
{
int i;
i = printf("letsfindcourse");
i = printf("%d ", i);
printf("%d ", i);
return 0;
}
A. letsfindcourse 15 3
B. letsfindcourse 14 2
C. letsfindcourse 14 3
D. Compilation Error
View Answer
Ans : C
Explanation: In C, printf() returns the number of characters successfully written on the output. Here letsfindcourse contain 14 character therefore i = 14 and then i is printed now again value of printf is assign but this time it print 3 since it contain 3 character %,d and space.
6. Output of this statment is :
printf ( "%d" , printf ( "hello" ) );
A. Syntex Error
B. hello5
C. gives garbage value
D. print hello and terminates
View Answer
Ans : B
Explanation: Firstly inner printf executes and will print hello now this return the number of character printed that is 5 and this will be printed by outer printf . Hence output is hello5
7. What is the output of this program?
#include <stdio.h>
# define scanf "%s Find best course "
main()
{
printf(scanf, scanf);
return 0;
}
A. %s Find best course Find best course
B. %s Find best course %s Find best course
C. Invalid Syntex
D. Run time error
View Answer
Ans : A
Explanation: printf statement will become printf("%s Find best course ", "%s Find best course ");
8. Which statment is true about the given code ?
#include <stdio.h>
int main()
{
printf("%d", main);
return 0;
}
A. Goes in infinite loop
B. Gives Address of function main.
C. Gives garbage value
D. Compilation Error
View Answer
Ans : B
Explanation: Name of the function is actually a pointer variable to the function and prints the address of the function.
9. What is the output of this program?
#include <stdio.h>
int main()
{
int i;
i = 1, 2, 3;
printf("%d", i);
return 0;
}
A. 1
B. 2
C. 3
D. Invalid Syntax
View Answer
Ans : A
Explanation: Associativity of comma operator is from left to right, but = operator has higher precedence than comma operator.Therefore the statement i = 1, 2, 3 is treated as i = 1 .
10. Comment on the given statment:
scanf("%d",i);
A. Will execute without any error
B. Will give Segmentation fault
C. Will give Compilation Error
D. None of the above
View Answer
Ans : B
Explanation: A segmentation fault occurs when a program attempts to access a memory location that it is not allowed to access, or attempts to access a memory location in a way that is not allowed.So as we can see segmentation fault occurs because program attempts to access a memory location that it is not allowed to access.
11. What is the output of this program?
#include <stdio.h>
int main()
{
int x = 1, y = 2;
printf("%d", x, y);
return 0;
}
A. 1
B. 2
C. Compilation Error
D. Garbage Value
View Answer
Ans : A
Explanation: None
12. What is the output of this program?
#include <stdio.h>
int main()
{
int x = 1, y = 2;
printf("%*d", x, y);
return 0;
}
A. 1
B. 2
C. Compilation Error
D. Garbage Value
View Answer
Ans : B
Explanation: None
13. What is the output of this program?
#include <stdio.h>
int main()
{
char str[25];
printf(" %d ",printf("c-letsfind"));
return 0;
}
A. 10 c-letsfind
B. 9 c-letsfind
C. c-letsfind 9
D. c-letsfind 10
View Answer
Ans : D
Explanation: Inner printf() will print first and then outer printf will display the length of the inner printf's string.
14. What is the output of this program?
#include <stdio.h>
# define loop while(true)
int main()
{
loop;
printf("c-letsfind");
return 0;
}
A. program never ends
B. c-letsfind
C. Compilation error
D. None of the above
View Answer
Ans : C
Explanation: error: 'true' undeclared (first use in this function)
15. What is the output of this program?
#include <stdio.h>
int main()
{
printf("%d", 5.00);
return 0;
}
A. Compilation error
B. Garbage value
C. 5
D. 0
View Answer
Ans : B
Explanation: The output is garbage value.
16. What is the output of this program?
#include <stdio.h>
int main()
{
printf("%d",5.25);
return 0;
}
A. Compilation error
B. Garbage value
C. 5
D. 0
View Answer
Ans : B
Explanation: 5.25 is neitheir a pure integer number(5) nor impure integer number(5.00).
17. What is the output of this program ?
#include <stdio.h>
int main()
{
int a = 3;
printf("%d");
return 0;
}
A. 3
B. Compilation error
C. Garbage value
D. Runtime error
View Answer
Ans : C
Explanation: As there is no declaration of variable a in printf function, a standard C compiler printf some garbage value as an output.
This program is tested under Dev cpp and in standard online c compiler.
18. What is the output of this program ?
#include <stdio.h>
int main()
{
char *ptr = "Hello World";
printf(ptr+2);
return 0;
}
A. pointer cannot be initialized
B. lo World
C. Runtime error
D. llo World
View Answer
Ans : D
Explanation: In printf, initial address of *ptr is incremented by 2 , thus it neglect He
19. What is the output of this program 32 bit c compiler ?
#include <stdio.h>
int main()
{
int a = 1;
printf("%d %p",a,a);
return 0;
}
A. Runtime error
B. 1 00000001
C. 1 1
D. %p is not a format specifier
View Answer
Ans : B
Explanation: %p is a format specifier to print a pointer in printf or sprintf.
For 64 bit c compiler, the output will be 1 0x1
20. What is the output of this program ?
#include <stdio.h>
static struct student
{
int a;
int b;
}
struct_var{2,3};
int main()
{
printf("%d %d",struct_var.a,struct_var.b);
return 0;
}
A. Runtime Error
B. Improper representation of structure variable
C. Compilation error
D. 2 3
View Answer
Ans : C
Explanation: It will give compilation error.
21. What is the output of the following code?
int main() {
int i=1;
i=2+2*i++;
printf("%d",i);
return 0;
}
A. 2
B. 3
C. 4
D. 5
View Answer
Ans : C
Explanation: For instance, this compiler gives 4 as the answer.
22. What is the output of the following code?
main ( )
{
int i;
i=1;
i=i+2*i++;
printf( "%d" , i);
}
A. 2
B. 3
C. 4
D. 5
View Answer
Ans : C
Explanation: 4 is the output of the following code.
23. What is the output of this program?
main()
{
int i;
i = 2+3, 4>3, 1;
printf( "%d" , i);
}
A. 1
B. 4
C. 3
D. 5
View Answer
Ans : D
Explanation: 5 is the output of this program.
24. What is the output of this program?
main ()
{
int i=5;
printf( "%d %d %d " , i,i<<2,i>>2);
}
A. 5 20 1
B. 5 1 20
C. 5 20 20
D. 5 1 1
View Answer
Ans : A
Explanation: << and >> operation applied on the value of "i" and we get the output.
25. What is the output of this program?
main ( )
{
int i=5;
printf( "%d %d %d " , i,i<<2,i<<2);
}
A. 5 20 1
B. 5 1 20
C. 5 20 20
D. 5 1 1
View Answer
Ans : C
Explanation: << operation applied on the value of "i" and we get the output.
26. What is the output of this program?
int main()
{
int i=5;
printf( "%d %d %d " , i,i<2,i>2);
return 0;
}
A. Compilation error
B. Garbage value
C. 5 0 1
D. 5 1 0
View Answer
Ans : C
Explanation: The code will successfully compiled and give output 5 0 1
27. What is the output of this program ?
int main()
{
int i=5;
printf( "%d %d %d " , i,i&&2,i||2);
return 0;
}
A. 5 1 1
B. Compilation error
C. Garbage value
D. 5 0 1
View Answer
Ans : A
Explanation: The code will successfully compiled and give output 5 1 1.
28. What is the output of this program ?
int main()
{
int i=5;
printf( "%d %d
" , i,i|2);
return 0;
}
A. 5 7
B. 5 1
C. Garbage value
D. 5 0
View Answer
Ans : A
Explanation: The code will successfully compiled and give output 5 7.
29. What is the output of this program 32 bit c compiler ?
int main()
{
int i=1;
i=i+i*i++;
printf("%d",i);
return 0;
}
A. 2
B. 3
C. 4
D. 5
View Answer
Ans : C
Explanation: The code will successfully compiled and give output 4.
30. What is the output of this program ?
int main()
{
int i=-2;
i=i+i*i++;
printf("%d",i);
return 0;
}
A. -2
B. 1
C. -1
D. -2
View Answer
Ans : B
Explanation: The code will successfully compiled and give output 1.
31. What is the output of the following code?
int main()
{
int k=1;
printf("%d == 1 is" "%s", k, k==1?"TRUE":"FALSE");
return 0;
}\
A. k == 1 is TRUE
B. 1 == 1 is TRUE
C. 1 == 1 is FALSE
D. K == 1 is FALSE
View Answer
Ans : B
Explanation: int k=1; The variable k is declared as an integer type and initialized to '1'.
printf("%d == 1 is" "%s
", k, k==1?"TRUE":"FALSE"); becomes
k==1?"TRUE":"FALSE"
1==1?"TRUE":"FALSE"
"TRUE"
Therefore the output of the program is 1 == 1 is TRUE
32. What is the output of the following code?
int main()
{
int k=2;
printf("%d == 1 is" "%s", k, k==1?"TRUE":"FALSE");
return 0;
}
A. k == 1 is TRUE
B. 2 == 1 is TRUE
C. 2 == 1 is FALSE
D. K == 1 is FALSE
View Answer
Ans : C
Explanation: the output of the program is 1 == 1 is False.
33. What is the output of this program?
char *str = "char *str = %c%s%c; main(){ printf(str, 4, str, 4);}";
int main()
{
printf(str, 4, str, 4);
return 0;
}
A. char *str = "char *str = %c%s%c; main(){ printf(str, 4, str, 4);}"; main(){ printf(str, 4, str, 4);}
B. char *str = %c%s%c; main(){ printf(str, 4, str, 4);}
C. No output
D. Error in program
View Answer
Ans : A
Explanation: char *str = "char *str = %c%s%c; main(){ printf(str, 4, str, 4);}"; main(){ printf(str, 4, str, 4);} is the output of this program.
34. What is the output of this program?
main ( )
{
float a=4.1589;
printf("%2.3f", a);
return 0;
}
A. 4
B. 4.159
C. 4.2
D. 4
View Answer
Ans : B
Explanation: float a=4.1589; The variable a is declared as an float data type and initialized to value 4.1589;
printf("%2.3f
", a); The precision specifier tells .3f tells the printf function to place three number after the .(dot).
Hence the output is 4.159
35. What is the output of this program?
main ( )
{
float a=4.1589;
printf("%2.1f", a);
return 0;
}
A. 4
B. 4.1
C. 4.2
D. 4
View Answer
Ans : C
Explanation: float a=4.1589; The variable a is declared as an float data type and initialized to value 4.1589;
printf("%2.1f
", a); The precision specifier tells .1f tells the printf function to place one after the .(dot).
Hence the output is 4.2
36. What is the output of this program?
int main()
{
printf("%c", ~('C'*-1));
return 0;
}
A. A
B. B
C. C
D. D
View Answer
Ans : C
Explanation: The code will successfully compiled and give output B.
37. What is the output of this program?
int main()
{
printf("%c", ~('W'*-1));
return 0;
}
A. S
B. T
C. U
D. V
View Answer
Ans : D
Explanation: The code will successfully compiled and give output V.
38. What is the output of this program ?
int main()
{
char *p;
p="%d";
p++;
p++;
printf(p-2, 13);
return 0;
}
A. 11
B. 13
C. Error
D. No output
View Answer
Ans : B
Explanation: The code will successfully compiled and give output 13.
39. What is the output of this program 32 bit c compiler ?
int main()
{
printf("%%%%");
return 0;
}
A. %%%%%
B. %%
C. No output
D. Error
View Answer
Ans : B
Explanation: The code will successfully compiled and give output %%.
40. What is the output of this program ?
int main()
{
int a=250;
printf("%1d<0x1d>", a);
return 0;
}
A. 1250
B. 2
C. 50
D. 250
View Answer
Ans : D
Explanation: int a=250; The variable a is declared as an integer type and initialized to value 250.
printf("%1d<0x1d>
", a); It prints the value of variable a.
Hence the output of the program is 250.
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