It depends on what you mean by "empty". If you just want a zero-length string, then your example will work.
This will also work:
buffer[0] = '\0';
If you want to zero the entire contents of the string, you can do it this way:
memset(buffer,0,strlen(buffer));
but this will only work for zeroing up to the first NULL character.
If the string is a static array, you can use:
memset(buffer,0,sizeof(buffer));
It depends on what you mean by "empty". If you just want a zero-length string, then your example will work.
This will also work:
buffer[0] = '\0';
If you want to zero the entire contents of the string, you can do it this way:
memset(buffer,0,strlen(buffer));
but this will only work for zeroing up to the first NULL character.
If the string is a static array, you can use:
memset(buffer,0,sizeof(buffer));
Two other ways are strcpy(str, ""); and string[0] = 0
To really delete the Variable contents (in case you have dirty code which is not working properly with the snippets above :P ) use a loop like in the example below.
#include <string.h>
...
int i=0;
for(i=0;i<strlen(string);i++)
{
string[i] = 0;
}
In case you want to clear a dynamic allocated array of chars from the beginning, you may either use a combination of malloc() and memset() or - and this is way faster - calloc() which does the same thing as malloc but initializing the whole array with Null.
At last i want you to have your runtime in mind. All the way more, if you're handling huge arrays (6 digits and above) you should try to set the first value to Null instead of running memset() through the whole String.
It may look dirtier at first, but is way faster. You just need to pay more attention on your code ;)
I hope this was useful for anybody ;)
Videos
My senior had a fit when he saw that in my code there were several initialization like
std::string str = "";
He told me to use
std::string str; str.clear();
He said using 1st method caused some "stl corruption crash" thing in production earlier, and didn't explain further, just said to used 2nd method always.
Can anyone explain how 1st method can lead to crash?
A couple of ways come to mind. Given that strings in C are usually terminated by an ASCII zero, the easiest would be to set the first byte to zero.
a[0] = '\0';
Now this doesn't erase all the characters in the string, but since the first character is now a termination character the string looks empty to your program.
If you want to erase all the characters in the string then you need to use a loop.
OR
Another way might be to use memset() to set the whole string to zeros.
memset(a, 0, strlen(a));
but this will only work for zeroing up to the first NULL character.
In your case, it should suffice to do:
a[0] = '\0';
This sets the first char in the string to be the null terminating character, such that when you print the string, it prints an empty string.
You should also assign the null terminating character to after the effective last character:
a[0] = 'a';
a[1] = 'b';
a[2] = '\0';
printf("%s", a); //print "ab"
Setting the text to the contents of your variable does not set up a permanent relationship between that variable and that text field, if you want to clear the text, you could use
output.setText("");
You have to clear the text from the JTextField object. Sending a variable as an argument with setText() does not tie that variable to the object. It simply copies the string.
output.setText("");
If the text is null or empty, has the effect of simply deleting the old text.
http://docs.oracle.com/javase/6/docs/api/javax/swing/text/JTextComponent.html#setText%28java.lang.String%29
It's not possible. There are 2 reasons for that
Python strings are immutable
Python implements a so called "call by sharing" evaluation strategy:
The semantics of call by sharing differ from call by reference in that assignments to function arguments within the function aren't visible to the caller
As noted by zerkms, it is strictly not possible, python does not pass argument by reference.
There are a few tricks that can be used as workarounds, such as passing a list or object, containing your string.
otherText=["hello"]
def foo(text):
text[0]="Goodbye string"
foo(otherText)
print(otherText) //Goodbye string