Register

C Programming

1,142 views
2 2 votes

long fun( char * s){
    long r = 0;
    for( ; *s ; r = (r << 1) | (*s++ - '0'));
    return r;
}

What does the fun("000001010") returns?

2 Answers

Best answer
3 3 votes

(*s++ - '0') this will subtract ascii value of stored character with ascii value of 0 and will give numeric (decimal ) value of stored character during each iteration,

example: ascii value of 0 and 1 is 48 and 49 , hence during iteration 1:

(*s++ - '0')=s[0]-'0'='0'-'0'=48-48=0(decimal value)

now evaluation of ur program is as given below : fun("000001010")

iteration r<<1 (*s++-'0')=value stored at s[i] r = r<<1|(*s++ - '0')
1 0 0 0
2 0 0 0
3 0 0 0
4 0 0 0
5 0 0 0
6 0 1 1
7 2 0 2
8 4 1 5
9 10 0 10
10   \n(ascii value 0) loop fail

therefore 10 will be return at the end

• selected by
1 1 vote
r   s

0  0                                                                                                                                                                            

0  0                                                                                                                                                                            

0  0                                                                                                                                                                            

0  0                                                                                                                                                                            

0  0                                                                                                                                                                            

0  1                                                                                                                                                                            

1  0                                                                                                                                                                            

2  1                                                                                                                                                                            

5  0     

at last r = r*2 = 10

 

return value will be 10
Voting & Accepting an answer helps improve the community
← Previous · sequential circuitsNext → · computer network
← Previous in category · DoubtNext in category → · Doubt
Position:
Show:

Related questions

1 1 vote
1 1 answer
241
241 views
khanshahima4 asked Sep 24
241 views
C programming , Doubt with the concepts of precedence , Associativity and Order of evaluation
1. If precedence tells me which operator has priority, and associativity tells me how to handle operators at the same level, then why do I need a separate concept called ...
14 14 votes
1 1 answer
1.3k
1.3k views
GO Classes asked Jul 2
1,314 views
GO Classes DPP | GATE CS | C Programming | Struct Padding
Assume:$\texttt{short = 2 bytes}$, $\texttt{int = 4 bytes}$, $\texttt{char = 1 byte}$$\texttt{int}$ needs $4$-byte alignment and the final structure size is rounded to a ...
17 17 votes
2 2 answers
720
720 views
GO Classes asked Jul 2
720 views
GO Classes DPP | GATE CS | C Programming | Struct Pointer
Assume:struct Student { double gpa; }; struct Student alice; struct Student *sptr = &alice;Which of the following correctly assigns $\texttt{4.0}$ to $\texttt{alice.gpa}$...
10 10 votes
1 1 answer
544
544 views
GO Classes asked Jul 2
544 views
GO Classes DPP | GATE CS | C Programming | Struct Copy
Consider the following code idea from the source:typedef struct { double x, y; } Point; void reset(Point p) { p.x = p.y = 0; } int main() { Point a = {12.0, 42.0}; Point ...