【Day05_0422】C Language multiple choice questions

1. The output of the following program is ？（D）

int x = 1;
do {
    
	printf("%2d\n", x++);
} while (x--);

A 1
B No output
C 2
D Fall into a dead cycle

2. Definition char dog[]=“wang\0miao”; that sizeof(dog) And strlen(dog) What are the differences ：（A）

A 10,4
B 4,4
C 9,9
D 9,4

analysis ：
\0 Occupy a byte space ,\ Indicates the escape character
The compiler will add a \0
strlen Function encountered \0 Stop counting after

3. The print result of the following program is ?（D）

char p1[15] = "abcd", * p2 = "ABCD", str[50] = "xyz";
strcpy(str + 2, strcat(p1 + 2, p2 + 1));
printf("%s", str);

A xyabcAB
B abcABz
C ABabcz
D xycdBCD
E Operation error

analysis ：

4. The output of the following program is （B）

#include<iostream.h>
void main() {
    
	int n[][3] = {
     10,20,30,40,50,60 };
	int(*p)[3];
	p = n;
	cout << p[0][0] << "," << *(p[0] + 1) << "," << (*p)[2] << endl;
}

A 10,30,50
B 10,20,30
C 20,40,60
D 10,30,60

analysis ：
p Represents a pointer to an array with three integer elements
p[0] Equivalent to *(p+0), Represents the second part of an array 0 That's ok , That is to say 0 Array name of a one-dimensional array , That is to say, No 0 Address of the first element of a one-dimensional array

5. What is correct in the following statement is （B）.

A C++ In program main() Functions must be placed at the beginning of the program
B C++ The entry function of the program is main function
C stay C++ In the program , The function to be called must be in main() Function

6. The running result of the following program is :（D）

#include<iostream>
using namespace std;
char fun(char x, char y) {
    
	if (x < y)
		return x;
	return y;
}
int main() {
    
	int a = '1', b = '1', c = '2';
	cout << fun(fun(a, b), fun(b, c));
	return 0;
}

A Operation error
B 2
C 3
D 1

7. about int* pa[5]; Description of , Which of the following is true （A）

A pa Is a person with 5 Pointer array of elements , Each element is a int Pointer to type ;
B pa Is a pointer to an array , The array pointed to is 5 individual int Element of type ;
C pa[5] The... Of a number 5 The value of the elements ;
D pa Is a pointer to the... In an array 5 Pointers to elements , The element is int Variable of type

8. The next two structures , stay #pragma pack(4) and #pragma pack(8) Under the circumstances , The sizes of the structures are （C）

struct One {
    
	double d;
	char c;
	int i;
}
struct Two {
    
	char c;
	double d;
	int i;
}

A 16 24,16 24
B 16 20,16 20
C 16 16,16 24
D 16 16,24 24

9. Which of the following pointer expressions can be used to reference array elements a[i] [j] [k] [l]（）

A (((a+i)+j)+k)+l)
B *(*(*(*(a+i)+j)+k)+l)
C (((a+i)+j)+k+l)
D ((a+i)+j+k+l)
His answer ： ( error )
right key ： B

analysis ：

10. Composed of multiple source files C Program , Edited 、 Preprocessing 、 compile 、 Linking and other stages will generate the final executable . Which of the following stages can you find that the called function is undefined ？（C）

A Preprocessing
B compile
C link
D perform

analysis ：
Preprocessing ： Header file expansion , Macro replace , Processing precompiled instructions , To comment, etc
compile ： Check for grammatical errors , Generate assembly code
assembly ： Translate the compiled assembly instructions into the corresponding binary files
link ： Splice multiple object files into one , Solve the address problem