Reading a comma delimited file to array
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Hi, I'm hitting a snag as I try to read back an array which has been written to a text file. Here's the relevant part of the code:
if((fp=fopen("myfile","r"))==NULL)
{
printf("Unable to open file.\n");
exit(1);
}
for(j=0;j<6;j++)
{
for(l=0;l<7;l++)
{
k=fgetc(fp);
if(k==",") break;
str2[j][l]=k;}}
fclose(fp);
for(j=0;j<6;j++)
{
for (l=0;l<7;l++)
{
printf("%c", str2[j][l]);
}
}This is generating an error: [Warning] comparison between pointer and integer. Though it runs, it is revealing that the break code which checks for a comma is not functioning as the compiler warns. Why is it claiming this is a pointer? Why is it saying anything about an integer when I've deliberately cast k as a character? Thanks for any input. ------ Update: The problem was solved by: (a) changing the double quotes to single quotes (apostrophes) and (b) switching
if(k==",") break;
below the assignment. In order to match the file derived string with one defined in code I also had to modify it:
str2[j][strlen(str2[j]-1]='\0';
as there is something foreign added in the file transfer process. Thanks, and if there is a mark as solved button I couldn't find it:)
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Hi, I'm hitting a snag as I try to read back an array which has been written to a text file. Here's the relevant part of the code:
if((fp=fopen("myfile","r"))==NULL)
{
printf("Unable to open file.\n");
exit(1);
}
for(j=0;j<6;j++)
{
for(l=0;l<7;l++)
{
k=fgetc(fp);
if(k==",") break;
str2[j][l]=k;}}
fclose(fp);
for(j=0;j<6;j++)
{
for (l=0;l<7;l++)
{
printf("%c", str2[j][l]);
}
}This is generating an error: [Warning] comparison between pointer and integer. Though it runs, it is revealing that the break code which checks for a comma is not functioning as the compiler warns. Why is it claiming this is a pointer? Why is it saying anything about an integer when I've deliberately cast k as a character? Thanks for any input. ------ Update: The problem was solved by: (a) changing the double quotes to single quotes (apostrophes) and (b) switching
if(k==",") break;
below the assignment. In order to match the file derived string with one defined in code I also had to modify it:
str2[j][strlen(str2[j]-1]='\0';
as there is something foreign added in the file transfer process. Thanks, and if there is a mark as solved button I couldn't find it:)
Try this: k=fgetc(fp); if(k==',') break; Hope that will work.
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Try this: k=fgetc(fp); if(k==',') break; Hope that will work.
Hi, Thanks for the reply. As far as I can see that's what I have except without the assignment to the array:
str2[j][l]=k
but that is basically what I'm trying to accomplish. The printing at the end is just to confirm that the file was successfully written to the array.
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Hi, Thanks for the reply. As far as I can see that's what I have except without the assignment to the array:
str2[j][l]=k
but that is basically what I'm trying to accomplish. The printing at the end is just to confirm that the file was successfully written to the array.
Replace the double-quotes in your comparison with single-quotes. In C and C++, double-quotes mean a pointer to a string of characters, but single-quotes mean a character literal.
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Hi, I'm hitting a snag as I try to read back an array which has been written to a text file. Here's the relevant part of the code:
if((fp=fopen("myfile","r"))==NULL)
{
printf("Unable to open file.\n");
exit(1);
}
for(j=0;j<6;j++)
{
for(l=0;l<7;l++)
{
k=fgetc(fp);
if(k==",") break;
str2[j][l]=k;}}
fclose(fp);
for(j=0;j<6;j++)
{
for (l=0;l<7;l++)
{
printf("%c", str2[j][l]);
}
}This is generating an error: [Warning] comparison between pointer and integer. Though it runs, it is revealing that the break code which checks for a comma is not functioning as the compiler warns. Why is it claiming this is a pointer? Why is it saying anything about an integer when I've deliberately cast k as a character? Thanks for any input. ------ Update: The problem was solved by: (a) changing the double quotes to single quotes (apostrophes) and (b) switching
if(k==",") break;
below the assignment. In order to match the file derived string with one defined in code I also had to modify it:
str2[j][strlen(str2[j]-1]='\0';
as there is something foreign added in the file transfer process. Thanks, and if there is a mark as solved button I couldn't find it:)
-
Replace the double-quotes in your comparison with single-quotes. In C and C++, double-quotes mean a pointer to a string of characters, but single-quotes mean a character literal.
Hi, thanks for your response. That helped. I also changed the control in the inside printf loop to
for(l=0;*(str2[j]+l);l++)
Now it's compiling with no warnings and is reading back pretty good text, though there is some stray characters after some of the words in the test text.
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Thanks Richard, I'm going to try to track down the errors in this code first and then experiment with this tokenizer. At this point I'm trying to get a really granular understanding of C which even means reinventing the wheel at times, just for my own edification:)
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Thanks Richard, I'm going to try to track down the errors in this code first and then experiment with this tokenizer. At this point I'm trying to get a really granular understanding of C which even means reinventing the wheel at times, just for my own edification:)
Jeffrey Webster wrote:
At this point I'm trying to get a really granular understanding of C which even means reinventing the wheel at times, just for my own edification:)
A good strategy. :thumbsup:
"One man's wage rise is another man's price increase." - Harold Wilson
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Thanks Richard, I'm going to try to track down the errors in this code first and then experiment with this tokenizer. At this point I'm trying to get a really granular understanding of C which even means reinventing the wheel at times, just for my own edification:)
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Just glancing at your code I would suggest using proper names for variables. Also, read up on the difference between a character and a string.
Thanks. This is just a test of concept program so I'm not doing 'real' variable names. As a former VB person I'm still in the CCAC (code cuss and cry) phase of learning C:)