Input / Output problems
- 1. To scan a and b given below, which of the following scanf() statement will you use?
#include<stdio.h> float a; double b;
Options- A. scanf("%f %f", &a, &b);
- B. scanf("%Lf %Lf", &a, &b);
- C. scanf("%f %Lf", &a, &b);
- D. scanf("%f %lf", &a, &b); Discuss
Correct Answer: scanf("%f %lf", &a, &b);
Explanation:
To scan a double value, %lf is used as format specifier.
Therefore, the answer is scanf("%f %lf", &a, &b);
- 2. Out of fgets() and gets() which function is safe to use?
Options- A. gets()
- B. fgets() Discuss
Correct Answer: fgets()
Explanation:
- 3. To print out a and b given below, which of the following printf() statement will you use?
#include<stdio.h> float a=3.14; double b=3.14;
Options- A. printf("%f %lf", a, b);
- B. printf("%Lf %f", a, b);
- C. printf("%Lf %Lf", a, b);
- D. printf("%f %Lf", a, b); Discuss
Correct Answer: printf("%f %lf", a, b);
Explanation:
To print a double value, %lf is used as format specifier.
Therefore, the answer is printf("%f %lf", a, b);
- 4. In a file contains the line "I am a boy\r\n" then on reading this line into the array str using fgets(). What will str contain?
Options- A. "I am a boy\r\n\0"
- B. "I am a boy\r\0"
- C. "I am a boy\n\0"
- D. "I am a boy" Discuss
Correct Answer: "I am a boy\n\0"
Explanation:
fgets reads characters from stream into the string s. It stops when it reads either n - 1 characters or a newline character, whichever comes first.
Therefore, the string str contain "I am a boy\n\0"
- 5. Which files will get closed through the fclose() in the following program?
#include<stdio.h> int main() { FILE *fs, *ft, *fp; fp = fopen("A.C", "r"); fs = fopen("B.C", "r"); ft = fopen("C.C", "r"); fclose(fp, fs, ft); return 0; }
Options- A. "A.C" "B.C" "C.C"
- B. "B.C" "C.C"
- C. "A.C"
- D. Error in fclose() Discuss
Correct Answer: Error in fclose()
Explanation:
- 6. What is the purpose of "rb" in fopen() function used below in the code?
FILE *fp; fp = fopen("source.txt", "rb");
Options- A. open "source.txt" in binary mode for reading
- B. open "source.txt" in binary mode for reading and writing
- C. Create a new file "source.txt" for reading and writing
- D. None of above Discuss
Correct Answer: open "source.txt" in binary mode for reading
Explanation:
- 7. Consider the following program and what will be content of t?
#include<stdio.h> int main() { FILE *fp; int t; fp = fopen("DUMMY.C", "w"); t = fileno(fp); printf("%d\n", t); return 0; }
Options- A. size of "DUMMY.C" file
- B. The handle associated with "DUMMY.C" file
- C. Garbage value
- D. Error in fileno() Discuss
Correct Answer: The handle associated with "DUMMY.C" file
Explanation:
t = fileno(fp); returns the handle for the fp stream and it stored in the variable t
printf("%d\n", t); It prints the handle number.
- 8. What does fp point to in the program?
#include<stdio.h> int main() { FILE *fp; fp=fopen("trial", "r"); return 0; }
Options- A. The first character in the file
- B. A structure which contains a char pointer which points to the first character of a file.
- C. The name of the file.
- D. The last character in the file. Discuss
Correct Answer: A structure which contains a char pointer which points to the first character of a file.
Explanation:
- 9. On executing the below program what will be the contents of 'target.txt' file if the source file contains a line "To err is human"?
#include<stdio.h> int main() { int i, fss; char ch, source[20] = "source.txt", target[20]="target.txt", t; FILE *fs, *ft; fs = fopen(source, "r"); ft = fopen(target, "w"); while(1) { ch=getc(fs); if(ch==EOF) break; else { fseek(fs, 4L, SEEK_CUR); fputc(ch, ft); } } return 0; }
Options- A. r n
- B. Trh
- C. err
- D. None of above Discuss
Correct Answer: Trh
Explanation:
Inside the while loop,
ch=getc(fs); The first character('T') of the source.txt is stored in variable ch and it's checked for EOF.
if(ch==EOF) If EOF(End of file) is true, the loop breaks and program execution stops.
If not EOF encountered, fseek(fs, 4L, SEEK_CUR); the file pointer advances 4 character from the current position. Hence the file pointer is in 5th character of file source.txt.
fputc(ch, ft); It writes the character 'T' stored in variable ch to target.txt.
The while loop runs three times and it write the character 1st and 5th and 11th characters ("Trh") in the target.txt file.
- 10. Which of the following operations can be performed on the file "NOTES.TXT" using the below code?
FILE *fp; fp = fopen("NOTES.TXT", "r+");
Options- A. Reading
- B. Writing
- C. Appending
- D. Read and Write Discuss
Correct Answer: Read and Write
Explanation:
More in C Programming:
Programming
Copyright ©CuriousTab. All rights reserved.