More on Argv
I'm trying to write my own clone of the UNIX utility Cut. Syntax as follows:
cut sourcefile -c1,15
I'm still getting familiar with argv and handling arguments passed to it. I realize that:
argv[0] = cut
argv[1] = sourcefile
argv[2] = -c1,15
When I'm processing the command line args, how can I check that argv[2] contains the "-c"?
cut sourcefile -c1,15
I'm still getting familiar with argv and handling arguments passed to it. I realize that:
argv[0] = cut
argv[1] = sourcefile
argv[2] = -c1,15
When I'm processing the command line args, how can I check that argv[2] contains the "-c"?
ASKER CERTIFIED SOLUTION
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SOLUTION
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PS: See also the function reference for 'strstr()' at bhttp://www.cplusplus.com/reference/clibrary/cstring/strstr.html
SOLUTION
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>> if( !strcmp("-c", argv[1], 1))
No :
if (!strncmp("-c", argv[1], 2))
with strncmp instead of strcmp and 2 instead of 1 :
http://www.cplusplus.com/reference/clibrary/cstring/strncmp.html
Btw, if you need to be able to recognize more command line options, then you probably want to parse it one character at a time :
char *ptr = argv[1];
if ('-' == *ptr) {
/* command line option found */
++ptr;
switch (*ptr) {
case 'c' :
/* we found "-c", so (ptr+1) points to something like "1,5" */
break;
/* other cases */
default :
/* unsupported command line option */
break;
}
}
No :
if (!strncmp("-c", argv[1], 2))
with strncmp instead of strcmp and 2 instead of 1 :
http://www.cplusplus.com/reference/clibrary/cstring/strncmp.html
Btw, if you need to be able to recognize more command line options, then you probably want to parse it one character at a time :
char *ptr = argv[1];
if ('-' == *ptr) {
/* command line option found */
++ptr;
switch (*ptr) {
case 'c' :
/* we found "-c", so (ptr+1) points to something like "1,5" */
break;
/* other cases */
default :
/* unsupported command line option */
break;
}
}
since '-' places in first position
if (argv[1][0] == '-')
...
if (argv[1][0] == '-')
...
>> if (argv[1][0] == '-')
That's what I had, no ?
char *ptr = argv[1];
if ('-' == *ptr)
That's what I had, no ?
char *ptr = argv[1];
if ('-' == *ptr)
ASKER
What's the difference between strncmp and !strncmp?
They are the same function, the ! means "not" or if the value returned is 0 (or false) then invert to non-zero (or true). In this case when strncmp returns 0 is means the strings being compared were equal so the if statement will need to evaluate to true when the strings are equal, so "!" was added to accomplish this.
ASKER
argv[0] = cut
argv[1] = -c1,5
argv[2] = filename
So I'd use:
if( !strcmp("-c", argv[1], 1))
?