C Language notes

1. The C language itself does not provide input and output statements,

Input and Output operations are implemented by functions. Some input and output functions are provided in the C standard function library, such as printf and scanf. When using them, do not mistakenly think that they are the "Input and Output statements" provided by the C language ". Printf and scanf are not Keywords of C language, but just function names. Functions provided by C are stored in the system in the form of libraries, which are not part of the C language text.

2,

If the variable has been correctly described as the float type, use the scanf statement ("% F", & A, & B, & C); to assign a to 10.0, B gives 22.0, C gives 33.0, incorrect input format is B

A. 10 <press enter> 22 <press enter> 33 <press enter>

B. 10.0, 22.0, 33.0 <press enter>

C. 10.0 <press enter> 22.0 33.0 <press enter>

D. 10 22 <press enter> 33 <press enter>

3. Pay attention to the semicolon after while

Int y =-5;

While (Y ++ );

Printf ("y = % d \ n", y );

The running result is y = 1.

4,

Which of the following function call statements is incorrect? d

A. X = (INT) power (B );

B. x = power (A + B );

C. x = power ();

D. x = float power ();

5,

Which of the following statements does not properly define a one-dimensional array? (d)

A. Int num [3];

B. # define N100 int num [N];

C. Int num [2*3];

D. Int n= 100; int num [N];

6,

Char A [3], B [] = "China ";

A = B;

Printf ("% s", );

Then (d)

A. The output will be China

B. Output ch

C. output the Chi

D. Compilation Error

Can not convert from 'Char [6] 'to 'Char [3]'

7,

The output result of the following program is:

Main ()

{Char s [] = "9876", * P;

For (P = s; P <S + 2; p ++)

Printf ("% s", P );

}

A. 9876 876

B. 9876

C. 876

D. No results

P = s; pointer P points to the first address of the S array. When output string % s, the entire string is 9876 from 9. After p ++, P = S + 1; pointer P points to S + 1, pointing to 8 of 9876. When the output string is % s, it starts from 8, after 876 P ++ is output, the loop condition is not true. The loop jumps out and the program ends. Therefore, the output is 9876.

8. Int I = 9999;
Printf ("% d \ n", printf ("% d", I ))));

Print first and then return value

Print the inmost I output 9999 first, and the return value of the printf function is 4 (4 digits are printed)

Then print the return value 4 of the innermost printf function on the second-to-last layer. The return value of the printf function is 1 (that is, one digit is printed)

Then, the bottom layer prints the return value 1 of the bottom layer printf function, and the return value of the printf function is 1 (that is, one digit is printed)

Then print the last-most-layer printf function's return value 1.

The final result is: 9999411.