Trying to fread and fwrite to a file in C | Together C & C++ | Page 1

rough comet Mar 10, 2024, 2:41 AM

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This is what im trying to achieve, but im having troulbe freading and fwriting correctly, with the correct positions as well

wicked warrenBOT Mar 10, 2024, 2:41 AM

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@rough comet

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rough comet Mar 10, 2024, 2:44 AM

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This is my code thus far:

📎 debug.c

rough comet Mar 10, 2024, 2:46 AM

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rough comet This is what im trying to achieve, but im having troulbe freading and fwriting c...

In contrast to the sample here, my positions seem to be wrong, not sure what im doing wrong :(

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Trying to fread and fwrite to a file in C

quasi sapphire Mar 10, 2024, 2:53 AM

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ping_thonk

rough comet Mar 10, 2024, 2:55 AM

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quasi sapphire <:ping_thonk:479502823797686292>

wrong role, mb
is there a c helper role

quasi sapphire Mar 10, 2024, 2:59 AM

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out of interest: which one did you ping? 😛

rough comet Mar 10, 2024, 3:11 AM

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my code broke

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so im broken

strange condor Mar 10, 2024, 4:47 AM

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You should just stack allocate your strings in the createContacts function, since you don't need that memory outside of the scope and it's a constant buffer size.

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Why do you expect choice to contain anything meaningful here? You declare (but do not initialize) it right before you compare it to "Yes"

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Looks like you write each string (including the null byte) individually and then you write a struct containing each position in the file for the values?

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Then you set the write position to be behind the information from the struct and write it again, overwriting some of the strings you wrote to the file

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In readContacts you fread the size of struct contact expecting to get something meaningful when you had written the strings there first

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Since none of these strings will have a space in them, I would just store these as space separated values on each line. To retrieve them later, read in the entire line with fgets and split it up on the spaces with strtok, strtok_r, or sscanf

strange condor Mar 10, 2024, 5:07 AM

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quasi sapphire out of interest: which one did you ping? 😛

I would bet they tried to ping @Chelp and it tabbed in as @Chelp

strange condor Mar 10, 2024, 5:09 AM

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strange condor Since none of these strings will have a space in them, I would just store these ...

You could even use fscanf directly on the file I suppose

rough comet Mar 10, 2024, 8:32 AM

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strange condor Then you set the write position to be behind the information from the struct and...

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tldr

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finding the size of each member, id, string first or offset for that matter, and then scanning using fgets made a difference

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as well as finding the structs and all its members sizes as wlel

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b4 fwirting

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to then get the correct positions

#Trying to fread and fwrite to a file in C