C tmpnam() function
C library function - tmpnam()
The tmpnam() function is used to generate a string that is a valid pathname that does not name an existing file.
Syntax:
char *tmpnam(char *s);
tmpnam() Parameters:
Name | Description | Required /Optional |
---|---|---|
s | Stores the file name in s. | Required |
Return value from tmpnam()
- Upon successful completion, tmpnam() shall return a pointer to a string.
- If no suitable string can be generated, the tmpnam() function shall return a null pointer.
Example: tmpnam() function.
Following example calls tmpnam() function to create a valid file name.
#include <stdio.h>
int main(void)
{
char *file_name;
if ((file_name = tmpnam(NULL)) !=NULL)
printf("%s can be used as a file name.\n", file_name);
else
printf("Cannot create a unique file name\n");
}
Output:
\sge4. can be used as a file name.
C Programming Code Editor:
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C Programming: Tips of the Day
Reading a string with scanf :
An array "decays" into a pointer to its first element, so scanf("%s", string) is equivalent to scanf("%s", &string[0]). On the other hand, scanf("%s", &string) passes a pointer-to-char[256], but it points to the same place.
Then scanf, when processing the tail of its argument list, will try to pull out a char *. That's the Right Thing when you've passed in string or &string[0], but when you've passed in &string you're depending on something that the language standard doesn't guarantee, namely that the pointers &string and &string[0] -- pointers to objects of different types and sizes that start at the same place -- are represented the same way.
Ref : https://bit.ly/3pdEk6f
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