Parsing string to long in C

Question

I've written a server in python and the client in C.

The python server send i.e. "1 1000\n" to the C client.

The C function that recieves this string should parse it into two long int's.

void receive_job() {
 char tmp_buffer[256];
 long start, stop;
 recv(sock, tmp_buffer, 255, 0);
 /*
 here I wonder how I can parse tmp_buffer to set start and stop values.
 */
}

I am not very proficient in C, so I would appreciate a comment on this.

ckruse · Accepted Answer · 2011-10-28 13:56:09Z

5

Have a look at strtol() or strtoul(), depending on your concrete data type:

char end;
long x = strtol(tmp_buffer,&end,10);
long y = strtol(end+1,NULL,10);

answered Oct 28, 2011 at 13:56

ckruse

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pmg · Accepted Answer · 2011-10-28 13:58:23Z

4

Use strtol.

char data[] = "1 1000\n";
char *next, *err;
long a = strtol(data, &next, 10);
long b = strtol(next, &err, 10);

answered Oct 28, 2011 at 13:58

pmg

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Ed Heal · Accepted Answer · 2011-10-28 13:57:25Z

2

Look up sscanf manual page - but check the return value!

answered Oct 28, 2011 at 13:57

Ed Heal

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Basile Starynkevitch · Accepted Answer · 2011-10-28 13:59:38Z

1

It is better to clear the tmp_buffer using memset before calling recv or at least to add a null byte in it. Otherwise it would contain garbage that you might parse if something got transmitted wrongly.

answered Oct 28, 2011 at 13:59

Basile Starynkevitch

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1 Comment

Dog eat cat world Over a year ago

thanks, I'm currently using sscanf with the expression "%ld %ld\n", so I reckon it shouldn't be necessary to clear the tmp_buffer.

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