Thread: Incompatible string assignment types

Gudday all
The biggest error I get with my C programming is incompatible assignment types of various flavours. In this case it is strings.

Code:

 char rptline[30];   //name of RPT file
 const size_t size = 64;
 struct _finddata_t fileData = {0};

// start a search for all files with an extension of "rpt"
 searchHandle = _findfirst("*.rpt", &fileData);
// if the search started
 if (searchHandle != -1) {
// print a banner

 rptFile = fopen (rpt_file, "w+");  /* open data file "rptFile.dat" for writing */
 do {
	// print the file name
	//puts(fileData.name);
	printf("----- The .rpt file(s) are %s -----\n", fileData.name);
	rptline = strcat(fileData.name, ".tmp");
	printf("--- The tmp rpt file name is % ---\n", rptline);
	//rename(fileData.name, )
	fprintf(rptFile, "%s", fileData.name);  /* write RPT file name to rptFile.dat file  */
		}

The fragment above shows my latest failure. I am trying to add the extension ".tmp " to a list of *.rpt files that I have found
e.g. I want to get 1.rpt.tmp, 2.rpt.tmp etc:
The problem occurs in the line

Code:

rptline = strcat(fileData.name, ".tmp");

The errror message is "error: incompatible types in assignment of `char*' to `char[30]' "
I assume that it does not accept that fileData.name is a string compatible with what strcat would expect. Yet in the line above viz.

Code:

printf("----- The .rpt file(s) are %s -----\n", fileData.name);

the program had no apparent trouble accepting fileData.name as a string.
Perhaps the initial assignment of fileData is a problem.

I find trying to sort what when pointers, contents of pointers etc: are to be used very confusing.

Ultimately all I want to do is rename existing *.rpt files to *.rpt.tmp. Maybe I am making a mountain out of a molehill?

Thanks spidey
The next problem I have is to rename an existing file that I have created with my code with the original filename using the rename function.

Code:

char oldrptname[22];  //name of last rpt file looked at
struct _finddata_t fileData = {0};

strcpy(oldrptname, fileData.name);
printf("oldrptname= %s\n", oldrptname);
rename("error.dat", <oldrptname>);

How would I put the filename stored as variable 'oldrptname' in the 2nd portion of the rename function?
I have tried combinations of *oldrptname, &oldrptname etc: but within success.
As noted earlier I can print out oldrptname successfully.
Unless having oldrptname as a string array is the problem and it would be better/easier to have it as just a char string?

This is a crazy idea, but it just might work: why not try "oldrptname"? (EDIT: Obviously, without the quotes when you use it in the program.)

No C reference will tell you that it's <cstdio>. A C++ reference will tell you that it is <cstdio>, because in C++ it is. In C it is <stdio.h> If you try <cstdio.h> it won't even compile (unless you have, advertently or inadvertently, renamed a header to that name).

rename returns success/failure, so check the return value. For instance, if error.dat is not in the current working directory, there won't be anything there to rename.

Originally Posted by tabstop

No C reference will tell you that it's <cstdio>. A C++ reference will tell you that it is <cstdio>, because in C++ it is. In C it is <stdio.h> If you try <cstdio.h> it won't even compile (unless you have, advertently or inadvertently, renamed a header to that name).

rename returns success/failure, so check the return value. For instance, if error.dat is not in the current working directory, there won't be anything there to rename.

Here is my sophisicated error checking. Can we find out what the error actually is?

Code:

int status;

status = rename("error.dat", oldrptname);
	if (status != 0)
	{
		printf("error found\n");
		}
		else {

			printf("No error found\n");
		}

I am having a non-zero error return so a fault is found.
The only thing I can think of of is that error.dat takes a finite time to appear in the directory. The code is probably looking at the directory before error.dat is created so naturally an error is returned.
2 alternatives
1. Have the program check for the existence of error.dat 1st
2. Have the program wait. It is a shame that this code is done at the end of the program. I have nothing else for the programme to do in the meantime.

Your indentation needs some work, there.

Probably this may help:

Code:

int status;
status = rename("error.dat", oldrptname);
if (status != 0) {
    perror("Problem renaming:");
}

Originally Posted by tabstop

Your indentation needs some work, there.

Probably this may help:

Code:

int status;
status = rename("error.dat", oldrptname);
if (status != 0) {
    perror("Problem renaming:");
}

Code:

status = rename("error.dat", oldrptname);
if (status != 0)
{
  perror("problem is:");
}
 else {
           printf("No error found\n");
        }

The error message is : File exists.
I am wondering is it is a permissions problem e.g. the program does not have the authority to cahnge the file's name.
See attachment

So it won't rename a file to a name that already exists. If oldrptname, whatever its value is, is a file that is already there, then nothing is going to happen. Pick a different name.