01
Among the following function definitions, the one that will cause a compilationerror is
A) max(int x, int y, int* z)
{ *z = x>y?x:y; }
B) int max(int x, y)
{ int z;
z = x>y?x:y;
return z;}
C) max(int x, int y)
{ int z;
z = x>y?x:y;
return(z);}
D) int max(int x, int y)
{ return (x>y ? x : y); }
Answer: B
Explanation:
For option B: The function parameter y does not have a declared type, which is illegal. The correct syntax should be int max(int x, int y)
02
Assuming a and b are int type variables, after executing the following statements, the value of b will be
a=1;b=10;
do
{b-=a;a++;}
while(b–<0);
A) 9
B) -2
C) -1
D) 8
Answer: D
Explanation: Brief
03
If we assume a=2, b=3, x=3.5, y=2.5
Then the value of the following arithmetic expression is
(float)(a+b)/2+(int)x%(int)y
A) 2
B) 3
C) 3.5
D) 2.5
Answer: C
Explanation:
Step-by-step calculation
(a + b):
a + b = 2 + 3 = 5 (int)
(float)(a + b):
Cast to float → 5.0f
(float)(a + b) / 2:
5.0f / 2 → 2.5f (float)
(int)x:
x = 3.5, cast to int → 3
(int)y:
y = 2.5, cast to int → 2
(int)x % (int)y:
3 % 2 → 1 (int)
Final addition:
2.5f + 1 → 3.5f (float)
04
The following code segment inputs data into all elements of the array, which statement should be filled in the blank
#include <stdio.h>
main()
{
int a[10],i=0;
while(i<10)
scanf(“%d”,______);
}
A) a+(++i)
B) &a[i+1]
C) a+i
D) &a[i++]
Answer: D
Explanation:
For option A: ++i will increment i first, causing the first loop to skip a[0] and possibly access a[10] (error)
For option B: In the first loop i=0, input to a[1], skipping a[0], in the last loop i=9, input to a[10] (out of bounds)
For option C: The syntax is correct (a+i is equivalent to &a[i]), but the loop variable i is not updated, leading to an infinite loop (error)
05
Which of the following options can be a valid integer in C language
A) 10110B
B) 0386
C) 0Xffa
D) x2a2
Answer: C
Explanation:
In C language, valid integers can take various forms:
1. Decimal: ordinary numbers;
2. Octal: starts with 0;
3. Hexadecimal: starts with 0x or 0X;
4. Binary: starts with 0b or 0B;
For option A:
Binary must include 0b or 0B
For option B:
Octal cannot contain 8
For option D:
Hexadecimal must include 0x or 0X
06
Read the following code segment:
main()
{ int i, s=0, t[]={1,2,3,4,5,6,7,8,9};
for(i=0;i<9;i+=2) s+=*(t+i);
printf(“%d\n”,s);
}
The output result after the program execution is
A) 45
B) 20
C) 25
D) 36
Answer: C
Explanation:
Define an array t and initialize it
Using a for loop, starting from i=0, increasing by 2 (i.e., i=0, 2, 4, 6, 8).
In the loop, calculate *(t + i) (i.e., t[i]), and accumulate it into variable s, finally output the value of s.
07
(Multiple choice) Among the following statementscorrect are
A) User-defined identifiers are allowed to use keywords
B) User-defined identifiers should aim to be “self-explanatory”
C) User-defined identifiers must start with a letter or underscore
D) User-defined identifiers are case-sensitive
Answer: BCD
Explanation:
For option A: User-defined identifiers are not allowed to use keywords
Keywords in C language (reserved words) cannot be used as identifiers, the following are the standard C language (C89/C99) keywords:
Data type related
int, char, float, double
short, long, signed, unsigned
void, _Bool (C99), _Complex (C99), _Imaginary (C99)
Control flow related
if, else, switch, case, default
for, while, do, break, continue
goto, return
Storage class and modifiers
auto, register, static, extern
const, volatile, restrict (C99)
Structures and unions
struct, union, enum
Others
sizeof, typedef
C11 new keywords (partially supported by some compilers)
_Alignas, _Alignof, _Atomic, _Generic, _Noreturn, _Static_assert, _Thread_local
08
(Multiple choice) Among the statements defining variablescorrect are
A) int _int;
B) double int_;
C) char For;
D) float US$;
Answer: ABC
Explanation:
For option D: Identifiers can only contain letters, digits, and underscores, $ is an illegal character, so US$ is an illegal variable name.
09 (Common Mistake)
(Multiple choice) Given the definitions: int k=1, m=2; float f=7.0; which of the following options conforms to C language syntax
A) k=k>=k
B) -k++
C) k%int(f)
D) k/(int)f
Answer: ABD
Explanation:
For option A: k >= k compares whether k is greater than or equal to k. Then assigns the result to k, which is completely legal.
For option B: k++ is a post-increment, first returning the value of k, then incrementing k to 2. Then taking the negative, this is a legal expression.
For option C: The correct syntax for type casting in C language is (int)f, not int(f), the correct syntax is k % (int)f.
For option D: (int)f casts f to int type. k / (int)f means 1 / 7, the result is 0.
10 (Common Mistake)
(Multiple choice) If there is a definition statement:
double x[5]={1.0,2.0,3.0,4.0,5.0}, *p=x; thenthe correct references to the elements of the x array are
A) *p
B) x[5]
C) *(p+1)
D) *x
Answer: ACD
Explanation:
For option B: A common mistake, the valid indices of the array x are 0 to 4, x[5] is out of bounds.
For option D: The array name x degrades to a pointer in the expression, *x is equivalent to x[0].