Starting

Question 1

Which are the 2 compilers used for C?

Answer 1

gcc and clang

Question 2

How to compile a file world.c in gcc?

Answer 2

gcc world.c -std =c90

Question 3

what are the different gcc compiler options and what are their uses?

Answer 3

The different gcc compiler options are

• -o: Name your executable
• -g: Add in debugging information
• -Wall: Give warnings
• -Wextra: Give additional warnings
• -O, O2, O3: Compiler optimization and different levels of it.

Question 4

What are the 2 stage compilation for gcc?

Answer 4

Compilation using the -c flag

Linking using the -o flag

Question 5

What is the size of char and is it implementation dependent?

Answer 5

The size of char on any computer will be 8bits

Question 6

What is the range of signed and unsigned chars

Answer 6

Unsigned chars: {0…255}

Signed chars: {-128….127}

Question 7

What is the order of the size of the types?

Which all data types are signed/unsigned by default?

Answer 7

The order is as follows

char < short < int < long < long long

Every type is signed by default except for chars

Question 8

What variables are initialized to 0.

Answer 8

Only global variables are initialized to 0

Question 9

What are print modifiers for float, shortest of %f,%e

Answer 9

float: %f

shortest of %f, %e: %g

Question 10

Print modifiers for hex, octal, long int and double

Answer 10

Hex: %x,

Octal: %o

long int: %li

double: %lf

Question 11

What to watch out for when using the print function:

Answer 11

The compilers don’t check to see if the number of type modifiers is equal to the number of arguments to be output.

Question 12

Precedence of operators

Answer 12

• Assignment is the lowest
• * / % are all equal
• relational operators > == and !=
• ++–(cast) this is evaluated from left to right
• addition and subtraction > relational operators

Question 13

What is #include

How to include a library header file?

Answer 13

include <curl></curl>

it is preprocessor directive. These are used to insert header files into the program. These header files are given the extension .h

Question 14

What is the scanf function?

Answer 14

The scanf function is used to read in input. It only contains conversion specifications

Question 15

What are the things to watch out for when using scanf?

Answer 15

• The programmer must make sure that the number of input specifiers matches the number of arguments
• The & symbol precedes the name of the variable and the programmer must make sure that this is included.
• Scanf also peeks at the final new line without reading it

Question 16

Outline how scanf works

Answer 16

1. Scanf reads the input by matching the input specifiers with the input data given to it.
2. it skips white spaces if necessary
3. It reads the input until there is a mismatch in the input specifiers
4. If everything is fine with one specifier then it moves onto the next specifier, eventually reading the whole line if nothing goes wrong.

Question 17

What are the modifers that can be used interchangeably in scanf?

Answer 17

The modifiers that can be used interchangeable are %e. %f, %g