C Strcmp Fails to Compare with Space
I Try to See If Formula[I] Is a Space and If It Is Number Should Be Zero. but Apparently It Fails to Compare Them: S I'm New to C, So Does Somebody Know the...
I try to see if formula[i] is a space and if it is number should be zero. But apparently it fails to compare them :S I'm new to C, so does somebody know the problem?
Note: this is not my whole code but only the essential part to understand the problem.
char formula[50] = "1 4 + 74 /";
int number = 0;
for (int i = 0; i != strlen(formula); i++)
{
if(!isdigit(formula[i]))
{
if (strcmp(&formula[i], " ") == 0)
{
number = 0;
}
}
}
4 Answers
It fails because the string " 4 + 74 /" is not equal to the string " ".
I think what you actually want to compare here are characters, which is as simple as
if (formula[i] == ' ')
{
// ...
}
For completeness sake, there is a way to perform a string comparison on a prefix of two strings, with the function strncmp, where you can specify how many characters of a string to match.
if (strncmp(&formula[i], " ", 1))
{
// ...
}
which would be equivalent to the caracter comparison above.
That is because they're not equal.
When you do &formula[i], you get a pointer to the character at location i. The string, viewed from that location, continues until the terminating '\0'-character, i.e. that's not a 1-character string.
Just do a direct comparison:
if(formula[i] == ' ')
strcmp compares two strings(two const char*s ending with a \0) and not two characters. In your case,use
if(formula[i]==' ')
The &formula[i] gives you a pointer to where i is allocated.
To tackle the problem , you have to do the following:
if (formula[i] == ' ')
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