Can variable i be accessed by functions in another source file?
int i;
int main()
{
printf("%d\n", i);
}
Answer: D
Correct answer: true
A variable at file scope has external linkage by default, so another source file can reach it by declaring extern int i;. Adding static to the definition is what would prevent that.
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If return type for a function is not specified, it defaults to int
Answer: A
Correct answer: True
Under the older rules an omitted return type defaulted to int - which is why so much old code writes main() rather than int main(). C99 removed the default, so a modern compiler will at least warn.
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Which of the following is true of a static variable?
Answer: C
Correct answer: All of the mentioned
All three are true of a static local variable. It keeps its value between calls, because it is initialised once and its storage lasts as long as the program; it therefore still exists after the function returns; and although its name is local, its address can be passed to another function, which may then modify it through the pointer.
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What is the notation for the following functions?
1. int f(int a, float b)
{
/* Some code */
}
2. int f(a, b)
int a; float b;
{
/* Some code */
}
Answer: C
Correct answer: 1. ANSI Notation 2. KR Notation
The first form declares each parameter’s type inside the parentheses - the ANSI (prototype) style, introduced by the 1989 standard. The second lists only the names in the parentheses and declares their types between the parentheses and the body - the old Kernighan and Ritchie style. The ANSI form matters because it lets the compiler check the arguments at every call; the K&R form does not, and is now obsolete.
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Can a function return an enumeration constant in C?
Answer: A
Correct answer: true
An enumeration constant is an integer constant, so a function can return one exactly as it returns any int - and a function may equally be declared to return the enumeration type itself.
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What is the output of this code having void return-type function?
void foo()
{
return 1;
}
void main()
{
int x = 0;
x = foo();
printf("%d", x);
}
Answer: C
Correct answer: Compile time error
A void function must not return a value, so return 1; is an error - and assigning the result of a void function to an int is a second one. Either alone would stop the program compiling.
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The output of the code below is
int *m();
void main()
{
int k = m();
printf("%d", k);
}
int *m()
{
int a[2] = {5, 8};
return a;
}
Answer: D
Correct answer: Varies
Two faults compound each other. The function returns a pointer to a local array that no longer exists, and the caller assigns that pointer to an int. What is printed is an address reinterpreted as an integer - different on every run and every machine.
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Maximum number of arguments that a function can take is 12
Answer: B
Correct answer: No
The standard sets no limit of twelve. It requires an implementation to support at least 127 parameters, and most allow far more - so the practical limit is the compiler’s, not the language’s. (A function needing many parameters is usually better given a structure.)
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What is the output of this C code?
static int x;
void main()
{
int x;
printf("x is %d", x);
}
Answer: A
Correct answer: Junk value
The local int x; shadows the file-scope static, and being an automatic variable with no initialiser it holds whatever was on the stack - a junk value. Only variables with static storage duration are zeroed for you.
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Functions cannot return more than one value at a time
Answer: A
Correct answer: True
A C function returns at most one value. Where more is needed the usual devices are to pass pointers for the extra results, or to return a structure containing them all.
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