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- Question
Point out the error in the following program.
#include<stdio.h> #include<stdarg.h> void varfun(int n, ...); int main() { varfun(3, 7, -11, 0); return 0; } void varfun(int n, ...) { va_list ptr; int num; num = va_arg(ptr, int); printf("%d", num); }
Options- A. Error: ptr has to be set at begining
- B. Error: ptr must be type of va_list
- C. Error: invalid access to list member
- D. No error
- Correct Answer
- Error: ptr has to be set at begining
ExplanationUsing va_start(ptr, int); - 1. Point out the error if any in the following program (Turbo C).
#include<stdio.h> #include<stdarg.h> void display(int num, ...); int main() { display(4, 'A', 'a', 'b', 'c'); return 0; } void display(int num, ...) { char c; int j; va_list ptr; va_start(ptr, num); for(j=1; j<=num; j++) { c = va_arg(ptr, char); printf("%c", c); } }
Options- A. Error: unknown variable ptr
- B. Error: Lvalue required for parameter
- C. No error and print A a b c
- D. No error and print 4 A a b c Discuss
- 2. Point out the error in the following program.
#include<stdio.h> #include<stdarg.h> int main() { void display(char *s, int num1, int num2, ...); display("Hello", 4, 2, 12.5, 13.5, 14.5, 44.0); return 0; } void display(char *s, int num1, int num2, ...) { double c; char s; va_list ptr; va_start(ptr, s); c = va_arg(ptr, double); printf("%f", c); }
Options- A. Error: invalid arguments in function display()
- B. Error: too many parameters
- C. Error: in va_start(ptr, s);
- D. No error Discuss
- 3. Point out the error in the following program.
#include<stdio.h> #include<stdarg.h> int main() { void display(int num, ...); display(4, 12.5, 13.5, 14.5, 44.3); return 0; } void display(int num, ...) { float c; int j; va_list ptr; va_start(ptr, num); for(j=1; j<=num; j++) { c = va_arg(ptr, float); printf("%f", c); } }
Options- A. Error: invalid va_list declaration
- B. Error: var c data type mismatch
- C. No error
- D. No error and Nothing will print Discuss
- 4. Point out the error in the following program.
#include<stdio.h> #include<stdarg.h> fun(...); int main() { fun(3, 7, -11.2, 0.66); return 0; } fun(...) { va_list ptr; int num; va_start(ptr, n); num = va_arg(ptr, int); printf("%d", num); }
Options- A. Error: fun() needs return type
- B. Error: ptr Lvalue required
- C. Error: Invalid declaration of fun(...)
- D. No error Discuss
- 5. Point out the error in the program.
#include<stdio.h> #define MAX 128 int main() { char mybuf[] = "India"; char yourbuf[] = "CURIOUSTAB"; char *const ptr = mybuf; *ptr = 'a'; ptr = yourbuf; return 0; }
Options- A. Error: unknown pointer conversion
- B. Error: cannot convert ptr const value
- C. No error
- D. None of above Discuss
- 6. Point out the error in the following program.
#include<stdio.h> #include<stdarg.h> void display(char *s, ...); void show(char *t, ...); int main() { display("Hello", 4, 12, 13, 14, 44); return 0; } void display(char *s, ...) { show(s, ...); } void show(char *t, ...) { int a; va_list ptr; va_start(ptr, s); a = va_arg(ptr, int); printf("%f", a); }
Options- A. Error: invalid function display() call
- B. Error: invalid function show() call
- C. No error
- D. Error: Rvalue required for t Discuss
- 7. Point out the error in the following program.
#include<stdio.h> #include<stdarg.h> void varfun(int n, ...); int main() { varfun(3, 7, -11.2, 0.66); return 0; } void varfun(int n, ...) { float *ptr; int num; va_start(ptr, n); num = va_arg(ptr, int); printf("%d", num); }
Options- A. Error: too many parameters
- B. Error: invalid access to list member
- C. Error: ptr must be type of va_list
- D. No error Discuss
- 8. The macro va_start is used to initialise a pointer to the beginning of the list of fixed arguments.
Options- A. True
- B. False Discuss
- 9. A function that receives variable number of arguments should use va_arg() to extract the last argument from the variable argument list.
Options- A. True
- B. False Discuss
- 10. va_list is an array that holds information needed by va_arg and va_end
Options- A. True
- B. False Discuss
Variable Number of Arguments problems
Search Results
Correct Answer: No error and print A a b c
Correct Answer: Error: in va_start(ptr, s);
Explanation:
We should have use
va_start(ptr, num2);
Correct Answer: Error: var c data type mismatch
Explanation:
Use
double instead of
float in
float c;
Correct Answer: Error: Invalid declaration of fun(...)
Explanation:
There is no fixed argument in the definition
fun()
Correct Answer: Error: cannot convert ptr const value
Explanation:
Step 1: char mybuf[] = "India"; The variable mybuff is declared as an array of characters and initialized with string "India".
Step 2: char yourbuf[] = "CURIOUSTAB"; The variable yourbuf is declared as an array of characters and initialized with string "CURIOUSTAB".
Step 3: char *const ptr = mybuf; Here, ptr is a constant pointer, which points at a char.
The value at which ptr it points is not a constant; it will not be an error to modify the pointed character; There will be an error only to modify the pointer itself.
Step 4: *ptr = 'a'; The value of ptr is assigned to 'a'.
Step 5: ptr = yourbuf; Here, we are changing the pointer itself, this will result in the error "cannot modify a const object".
Correct Answer: Error: invalid function show() call
Explanation:
The call to
show() is improper. This is not the way to pass variable argument list to a function.
Correct Answer: Error: ptr must be type of va_list
Correct Answer: False
Correct Answer: False
Correct Answer: True
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