Python C equivalence of this ternary operator

Question

I want to program this function from C to Python but the condition on the return is hard to convert:

In C:

int pos(int b) {
    char *r = strchr(a, b);
    return r?(r - a):-1;
}

Here what I tried:

def pos(b) :
    r = alphabet[a.rfind(b):]
    return r if (r - len(a)) else -1

The r variable is the same but the problem is the ternary operator. So of course, it doesn't do the same work :/ Can you help me?

if you are looking for a ternary operator in python this post might help http://stackoverflow.com/questions/394809/does-python-have-a-ternary-conditional-operator — badiya, May 06 '17 at 10:19

score 7 · Accepted Answer · answered May 06 '17 at 10:21

The Python ternary operator goes in a different order than the C ternary operator. The C ternary operator is in the form:

condition ? expr_if_true : expr_if_false

Whereas the Python version of this is in the form:

expr_if_true if condition else expr_if_false

score 0 · Answer 2 · answered May 06 '17 at 10:21

0

return r?(r - a):-1;

Is the same as

if (r != NULL) return r - a;
else           return -1;

answered May 06 '17 at 10:21

pmg

1

In the C code, a is a char and I dont know how to substrate strings in python – Alpacah May 06 '17 at 10:25
@Alpacah `a` is a `char *`, so `r-a` is the index of `a` in `r`. – mch May 06 '17 at 10:32

2 Answers2