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C++

软件笔试题

2016-05-13 09:34:21 admin 返回上一页

1. How do you code an infinite loop in C?
2. Volatile:
(1)What does the keyword volatile mean? Give an example
(2)Can a parameter be both const and volatile? Give an example
(3)Can a pointer be volatile? Give an example
3. What are the values of a, b, and c after the following instructions:
int a=5, b=7, c;
c = a+++b;
4. What do the following declarations mean?
(1)const int a;
(2)int const a;
(3)const int *a;
(4)int * const a;
(5)int const * a const;
5. Which of the following statements describe the use of the keyword stati
c?
(1)Within the body of a function: A static variable maintains its value
between function revocations
(2)Within a module: A static variable is accessible by all functions wit
hin that module
(3)Within a module: A static function can only be called by other functi
ons within that module
6. Embedded systems always require the user to manipulate bits in register
s or variables. Given an integer variable a, write two code fragments.
The first should set bit 5 of a. The second shnuld clear bit 5 of a. In bo
th cases, the remaining bits should be unmodified.
7. What does the following function return?
char foo(void)
{
unsigned int a = 6;
iht b = -20;
char c;
(a+b > 6) ? (c=1): (c=0);
return c;
}
8. What will be the output of the following C code?
main()
{
int k, num= 30;
k =(num > 5 ? (num <=10 ? 100:200): 500);
printf(“%d”, k);
}
9. What will the following C code do?
int *ptr;
ptr =(int *)Ox67a9;
*ptr = Oxaa55;
10. What will be the output of the follow C code?
#define product(x) (x*x)
main()
{
int i = 3, j, k;
j = product(i++);
k = product(++i);
printf(“%d %d”,j,k);
}
11. Simplify the following Boolean expression
!((i ==12) || (j > 15))
12. How many flip-flop circuits are needed to divide by 16?
13. Provides 3 properties that make an OS, a RTOS?
14. What is pre-emption?
15. Assume the BC register value is 8538H, and the DE register value is 62
A5H.Find the value of register BC after the following assembly operations:
MOV A,C
SUB E
MOV C,A
MOV A,B
SBB D
MOV B,A
16. In the Assembly code shown below
LOOP: MVI C,78H
DCR C
JNZ LOOP
HLT
How many times is the DCR C Operation executed?
17. Describe the most efficient way (in term of execution time and code si
ze) to divide a number by 4 in assembly language
18. what value is stored in m in the following assembly language code frag
ment if n=7?
LDAA #n
LABEL1: CMPA #5
BHI L3
BEQ L2
DECA
BRA L1
LABEL2: CLRA
LABEL3: STAA #m
19. What is the state of a process if a resource is not available?
#define a 365*24*60*60
20. Using the #define statement, how would you declare a manifest constant
that returns the number of seconds in a year? Disregard leap years in your an
swer.
21. Interrupts are an important part of embedded systems. Consequently, ma
ny compiler vendors offer an extension to standard C to support interrupts. Ty
pically, the keyword is __interrupt. The following routine (ISR). Point out pr
oblems in the code.
__interrupt double compute_area (double radius)
{
double area = PI * radius * radius;
printf(“\nArea = %f”, area);
return area;
}


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