How do I deal with this c programming question and if my viewpoint is right?

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When I study c programming on linux,I see the linux API.
The file function: int open( const char * pathname,int flags, mode_t mode);
and it said,if success return file descriptor,else -1.
if it means we can't decide when it return -1 and when success?
Suppose that,if it means we can't ensure the validity of a program.But how can we realize a system like oracle DBA.
And most demos in books often use many "if statement' to judge the result and then do the next step.
For example:

C++

int f;
f=open("outfile",O_RDWR|O_CREAT,0664);
if(f!=-1){
 if(write(f,"12345",i)!=i)
       perror("write error");
}
else
 perror("open failed");

Since we don't know how it return -1,why we judge it?Even if we judge it,we can get nothing.Why not ingore it,and then at the end of the program,we just give a output and tell it successes.If we have not get the output,means we failed.And according to my solution,we leave many "if statement" out,our program's speed will improve.
my code:

C++

int f;
open("outfile",O_RDWR|O_CREAT,0664);
write(f,"12345",i);
printf("success\n");

why not we did this?Can you help me,and I will appreciate it.

Posted 5-Mar-14 20:46pm

Member 10629059

Updated 5-Mar-14 20:51pm

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ)

v2

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[no name] 6-Mar-14 4:31am

A truly existential question. Maybe you should try philosophy.

2 solutions

Solution 2

That is an odd question. If you call a friend in the opposite end of the world and ask him whether it rains in his place, will you change his response to your preference, too? If your plane crashes, aren't you affected because you simply don't accept that the engine just caught fire?

More importantly: why do you even call a function - any function - if you don't care whether it succeeds or not? Why do you even write a program if you don't care whether it does what it's supposed to do?

Posted 5-Mar-14 22:08pm

Stefan_Lang

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Member 10629059 6-Mar-14 4:32am

Thank you.

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OriginalGriff · Accepted Answer · 2014-03-05T21:21:00

"it means we can't decide when it return -1 and when success?"
No, you can't - that's the whole point.

Think of it this way: you want to open a file so you can write some stuff into it, so you call the method to open the file. If the file is already open because some other program is writing to the same file, you can't open it - but you can't predict that. If it can't open it for any reason, it returns an error value.

Perhaps an analogy will help: you are driving down the road and understandably don't want to stop. Ahead is a set of traffic lights: you have no control over the lights - they are on a timer - but if they "go red" you MUST stop. If you don't there is likely to be a nasty accident.
The file open function checks the traffic lights: if they are green, it lets you continue. If they are red it returns a value specifically to let you know so you can respond (and either try again in a moment, or report a problem to your user and do something else)