The variable ' str ' is being used without being defined problem

The following error occurs when working with char data in C:

Run-time Check Failure #3-the variable ' str ' is being used without being defined.

This is typically caused by not allocating storage space to the char* str when it is defined.

Such as:

char* str;

strcpy (str, "string");

The above error will occur.

But if it is defined as:

Char str[10];//Note that the string length is at least greater than one character below the string length.

strcpy (str, "string");

There will be no error.

The character space of Str can also be allocated dynamically.

char* str;

str = (char*) malloc (strlen ("string") *sizeof (char));

strcpy (str, "string");

This problem may also occur when there is an access violation occurring at the write location.

Such as:

Unhandled exception at 0x102aece9 (Msvcr80d.dll) in XX.exe: 0xC0000005: Access violation when writing to location 0x004156b4