C language questions Help explain, help me explain the C language multiple choice questions

An escape character is a special form of representation of characters in the C language. Escape characters are commonly used to represent non-printable control characters and function-specific characters in the ASCII character set, such as the one-apostrophe (which is used to represent character constants'), which is used to represent a double apostrophe (") and backslashes (etc. Escape characters are represented by a backslash followed by a character or an octal or hexadecimal number.

Escape character meaning ascii code value (decimal).

A Bell (bel) 007

b Backspace (BS) 008

f Page change (FF) 012

n Line Break (LF) 010

r Carriage Return (CR) 013

T Horizontal Tabulation (HT) 009

v Vertical Tabulation (VT) 011

Backslash 092

Question mark character 063

Single quotation mark character 039

Double quotation mark character 034

0 null character (null) 000

ddd any character in three-digit octal.

xhh arbitrary character two-digit hexadecimal

a, c, and b are all escaped. d is a character pointer, which is an address value, and the assignment cannot be a character.

\xhh'Indicates hexadecimal.

ddd'Indicates occimal system.

Representation symbol So a='\';b='\xbc'That's right; Neither c nor d is correct.

This character should not be represented in this way'\\'This means because it is special.

c='\0xab'This one is even more wrong, it's a character channel.

0 is a character, followed by a number.

d="\0127";The statement is incorrect.

Because d is the pointer.

Introduction to QC Language for Beginners Lecture 4 Operators and Expressions.

Introductory Lecture on DC Language for Beginners Lecture 5 Input and Output (1) Introductory Lecture for Beginners in C Language Lecture 5 Input and Output (2) Introductory Lecture for Beginners in RC Language Lecture 6 Branching Structure (1) Introductory Lecture for Beginners in C Language Lecture 6 Branching Structure (2) Introductory Lecture for Beginners in C Language Lecture 7 Circular Structure.

Introductory Lecture 8 for Beginners in the C Language Lecture 8 Transfer Sentences.

HC Language Introductory Lecture 9 Array (1) IC Language Introductory Lecture 1 Introduction.

You'll want to think about escaping characters!

Choosing b for the A:C language, the real type is stored with double and float, and the int is stored for the integer, and the real type is stored in the form of scientific counting, and after a series of transformations are stored, there will be a part of the data lost when reading and calling (of course, the error is very small), so the result after participating in the operation is not accurate (refer to the relevant knowledge of float for details). For real and integer, it can only be said that the real type can represent a wide range of data, but it cannot be said that the calculation is more accurate.

For b: arrays are allocated with a contiguous memory space, and for a[5][5], the first data in the second row, a[1][0] can be represented by a[5].

For C: The option is incomplete, but after executing a=b, a should be a symbolic variable, and after the assignment statement is executed, the result of the operation on the right side of the equation is generally forcibly converted to the type on the left side of the equation.

Item C is correct. The reason for the error of a is that if the random number generated is 4, the loop will be skipped, note that the loop operation will be ended, so it will not necessarily run 8 loops fixedly, which also negates option b If 0 is generated, the loop will be terminated directly, but the program will not end the execution.

Question 1:

Trinocular operator, from right to left.

The question is equivalent to ac:d), first count the brackets, if ca:33, because a second question:

Enumeration type. If the enumeration type is defined without an initial value, 0 will be assigned to the first element by default, and the following elements will be +1;

It is also possible to assign an initial value to any member at the time of definition, and the default value is used for the unassigned initial value, that is, 1 larger than the previous element.

In the question, blue=10, the following white is not assigned, then it is 11, and the black after it is not assigned, then it is 1 larger than the previous white, so the value of black is 12.

The mistake of B in question 81 is that the size of the array is not specified, and the size must be specified when the array is defined.

The mistake of C in question 81 is to specify the size of the array with the value of the variable, and the size must be specified by a constant when the array is defined, and the variable cannot be used.

The C of problem 82 auto-increments the array name, which is not allowed.

The e of problem 82 accesses the 11th element of the array, but the array only has 10 elements, so this is also wrong.

is wrong.

It's all wrong.

Select the size of a union (union) to take the data type with the largest memory occupation, and int, long, and float are all 4 bytes, so the answer is 4 bytes.