Conditional Statements

[Gregc.]

Hi

I am writing a conditional statement, using strcat. What I am trying
to do is to add the file extenstion '.txt' if it doesn't already exist.
What I am having trouble with is returning a value if one already
exists. Attached is the code below:

#include <stdio.h>
#include <string.h>
const int MAX_FILENAME = 256;
oid checkFilename (char *filename, char *extension)
{
int length;
int check;
length = strlen(filename );
check=strcmp(fi lename,extensio n);

if(check==0)
return;
else
strcat(filename ,extension);

return;
int main () {
char filename1 [MAX_FILENAME] = "testfile";
char filename2 [MAX_FILENAME] = "testfile.t xt";
char filename3 [MAX_FILENAME] = "testfile.d at";
char extension [] = ".txt";

checkFilename (filename1, extension);
checkFilename (filename2, extension);
checkFilename (filename3, extension);

printf("1: %s\n", filename1);
printf("2: %s\n", filename2);
printf("3: %s\n", filename3);
}

Could someone point me in the right direction.

Greg

[Zero]

Gregc. schrieb:

Hi

I am writing a conditional statement, using strcat. What I am trying
to do is to add the file extenstion '.txt' if it doesn't already exist.
What I am having trouble with is returning a value if one already
exists. Attached is the code below:

#include <stdio.h>
#include <string.h>
const int MAX_FILENAME = 256;
oid checkFilename (char *filename, char *extension)
{
int length;
int check;
length = strlen(filename );
check=strcmp(fi lename,extensio n);

if(check==0)
return;
else
strcat(filename ,extension);

return;
int main () {
char filename1 [MAX_FILENAME] = "testfile";
char filename2 [MAX_FILENAME] = "testfile.t xt";
char filename3 [MAX_FILENAME] = "testfile.d at";
char extension [] = ".txt";

checkFilename (filename1, extension);
checkFilename (filename2, extension);
checkFilename (filename3, extension);

printf("1: %s\n", filename1);
printf("2: %s\n", filename2);
printf("3: %s\n", filename3);
}

Could someone point me in the right direction.

Greg

One solution, which works but has to be checked clearly :)

#include <stdio.h>
#include <string.h>

#define MAX_FILENAME 256

void checkFilename (char *filename, char *extension)
{
int length;
int check;
char * pToString;

if(!strstr(file name,extension) )
{
pToString = strchr(filename ,'.');

if (pToString)
{
pToString[1] = 't';
pToString[2] = 'x';
pToString[3] = 't';
pToString[4] = '\0';
}
else
{
strcat(filename ,extension);
}
}
}

int main () {

char filename1[MAX_FILENAME] = "testfile";
char filename2[MAX_FILENAME] = "testfile.t xt";
char filename3[MAX_FILENAME] = "testfile.d at";

char extension [] = ".txt";

checkFilename (filename1, extension);
checkFilename (filename2, extension);
checkFilename (filename3, extension);
printf("1: %s\n", filename1);
printf("2: %s\n", filename2);
printf("3: %s\n", filename3);

getch();
}

[Abdo Haji-Ali]

Zero wrote:

One solution, which works but has to be checked clearly :)

#include <stdio.h>
#include <string.h>

#define MAX_FILENAME 256

void checkFilename (char *filename, char *extension)
{
int length;
int check;
char * pToString;

if(!strstr(file name,extension) ) Consider the situation "BlatxtBla. ext"
{
pToString = strchr(filename ,'.'); Consider the situation "Bla.Bla.ex t"

if (pToString)
{
pToString[1] = 't';
pToString[2] = 'x';
pToString[3] = 't';
pToString[4] = '\0';
}
else
{
strcat(filename ,extension); Consider the situation where the buffer is not big enough to hold the
extenstion
}
}
}

int main () {

char filename1[MAX_FILENAME] = "testfile";
char filename2[MAX_FILENAME] = "testfile.t xt";
char filename3[MAX_FILENAME] = "testfile.d at";

char extension [] = ".txt";

checkFilename (filename1, extension);
checkFilename (filename2, extension);
checkFilename (filename3, extension);
printf("1: %s\n", filename1);
printf("2: %s\n", filename2);
printf("3: %s\n", filename3);

getch(); Where's the return statement?
}

Abdo Haji-Ali
Programmer
In|Framez

[CBFalconer]

"Gregc." wrote:

I am writing a conditional statement, using strcat. What I am
trying to do is to add the file extenstion '.txt' if it doesn't
already exist. What I am having trouble with is returning a
value if one already exists. Attached is the code below:

Look up strrchr() function.

--
"If you want to post a followup via groups.google.c om, don't use
the broken "Reply" link at the bottom of the article. Click on
"show options" at the top of the article, then click on the
"Reply" at the bottom of the article headers." - Keith Thompson
More details at: <http://cfaj.freeshell. org/google/>
Also see <http://www.safalra.com/special/googlegroupsrep ly/>

[Fred Kleinschmidt]

"Abdo Haji-Ali" <ah***@inframez .com> wrote in message
news:11******** *************@t 31g2000cwb.goog legroups.com...

Zero wrote:

One solution, which works but has to be checked clearly :)

#include <stdio.h>
#include <string.h>

#define MAX_FILENAME 256

void checkFilename (char *filename, char *extension, int maxlen)
{
int length;
int check;
char * pToString;

if(!strstr(file name,extension) )

Consider the situation "BlatxtBla. ext"

{
pToString = strchr(filename ,'.');

Consider the situation "Bla.Bla.ex t"

if (pToString)
{
pToString[1] = 't';
pToString[2] = 'x';
pToString[3] = 't';
pToString[4] = '\0';
}
else
{
strcat(filename ,extension);

Consider the situation where the buffer is not big enough to hold the
extenstion

}
}
}

int main () {

char filename1[MAX_FILENAME] = "testfile";
char filename2[MAX_FILENAME] = "testfile.t xt";
char filename3[MAX_FILENAME] = "testfile.d at";

char extension [] = ".txt";

checkFilename (filename1, extension);
checkFilename (filename2, extension);
checkFilename (filename3, extension);
printf("1: %s\n", filename1);
printf("2: %s\n", filename2);
printf("3: %s\n", filename3);

getch();

Where's the return statement?

}

Abdo Haji-Ali
Programmer
In|Framez

checkFileName( filename, extension, MAX_FILENAME );

int checkFilename (char *filename, char *extension, int maxlen) {
size_t nchf, nche;
char *p = NULL;
if ( filename!=NULL && extension != NULL ) {
nche = strlen( extension);
nchf = strlen( filename );
if ( nchf > nche ) {
p = &filename[nchf-nche];
}
else {
p = filename;
}
if ( strcmp( p, extension ) != 0 ) {
if ( nchf+nche < maxlen ) {
strcpy( p, extension );
return 0; /* success */
}
}
}
return 1; /* failed to add extension */
}
--
Fred L. Kleinschmidt
Boeing Associate Technical Fellow
Technical Architect, Software Reuse Project

[Abdo Haji-Ali]

Fred Kleinschmidt wrote:

int checkFilename (char *filename, char *extension, int maxlen) {
size_t nchf, nche;
char *p = NULL;
if ( filename!=NULL && extension != NULL ) {
nche = strlen( extension);
nchf = strlen( filename );
if ( nchf > nche ) {
p = &filename[nchf-nche];
}
else {
p = filename;
}
if ( strcmp( p, extension ) != 0 ) {
if ( nchf+nche < maxlen ) {
strcpy( p, extension );
return 0; /* success */
}
}
}
return 1; /* failed to add extension */
}

This function doesn't append the extention when necessary, it replaces
the last 'nche' (length of extenstion) characters of the file name with
the extension... Consider the situation when filename is "Blah" and the
extenstion is ".txt" the returned file name would be just ".txt";
which, I believe, isn't what the OP wanted.

Abdo Haji-Ali
Programmer
In|Framez

[Keith Thompson]

CBFalconer <cb********@yah oo.com> writes:

"Gregc." wrote:

I am writing a conditional statement, using strcat. What I am
trying to do is to add the file extenstion '.txt' if it doesn't
already exist. What I am having trouble with is returning a
value if one already exists. Attached is the code below:

Look up strrchr() function.

I'm not sure that strrchr() is going to be useful. It searches for a
single character; the OP wants to determine whether the name ends in a
specified string.

An outline of a solution:

If the name is less than 4 characters long, it doesn't end in
".txt".

Get a pointer to the fourth-to-last character of the string. Use
strcmp() to compare the (sub)string pointed to by that pointer to
".txt".

This is easily generalizable to arbitrary suffixes.

And if you append the ".txt", make sure you've allocated enough memory
to hold it.

--
Keith Thompson (The_Other_Keit h) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[Fred Kleinschmidt]

"Abdo Haji-Ali" <ah***@inframez .com> wrote in message
news:11******** **************@ j33g2000cwa.goo glegroups.com.. .

Fred Kleinschmidt wrote:

int checkFilename (char *filename, char *extension, int maxlen) {
size_t nchf, nche;
char *p = NULL;
if ( filename!=NULL && extension != NULL ) {
nche = strlen( extension);
nchf = strlen( filename );
if ( nchf > nche ) {
p = &filename[nchf-nche];
}
else {
p = filename;
}
if ( strcmp( p, extension ) != 0 ) {
if ( nchf+nche < maxlen ) {
strcpy( p, extension );
return 0; /* success */
}
}
}
return 1; /* failed to add extension */
}
This function doesn't append the extention when necessary, it replaces
the last 'nche' (length of extenstion) characters of the file name with
the extension... Consider the situation when filename is "Blah" and the
extenstion is ".txt" the returned file name would be just ".txt";
which, I believe, isn't what the OP wanted.

Oops - it should be
strcpy( filename, extension );

Abdo Haji-Ali
Programmer
In|Framez

--
Fred L. Kleinschmidt
Boeing Associate Technical Fellow
Technical Architect, Software Reuse Project

[Abdo Haji-Ali]

Fred Kleinschmidt wrote:

"Abdo Haji-Ali" <ah***@inframez .com> wrote in message

This function doesn't append the extention when necessary, it replaces
the last 'nche' (length of extenstion) characters of the file name with
the extension... Consider the situation when filename is "Blah" and the
extenstion is ".txt" the returned file name would be just ".txt";
which, I believe, isn't what the OP wanted.

Oops - it should be
strcpy( filename, extension );

Which is even worse, it replaces the filename with the extension... I
think you meant:
strcat( p, extension );

Abdo Haji-Ali
Programmer
In|Framez

[Mark McIntyre]

On Wed, 26 Apr 2006 18:04:55 GMT, in comp.lang.c , Keith Thompson
<ks***@mib.or g> wrote:

CBFalconer <cb********@yah oo.com> writes:

Look up strrchr() function.

I'm not sure that strrchr() is going to be useful. It searches for a
single character; the OP wants to determine whether the name ends in a
specified string.

starting with a dot. He can search for dots, and check that the
remaining part of the string a) has no more dots in it and b) is the
right pattern.

--
Mark McIntyre

"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it."
--Brian Kernighan