On Wed, Apr 21, 2010 at 10:19:34AM -0700, Harold Lee wrote:
> I've used static analysis tools before, and they find many many more
> bugs than compilers do.
>
> http://en.wikipedia.org/wiki/List_of_tools_for_static_code_analysis
>
> They list tools for Python, Perl, PHP and JavaScript, proving that
> dynamic languages can be safe too. These tools go much farther than a
> type system by following the data flow in and out of functions.
>
> http://stackoverflow.com/questions/141498/what-open-source-c-static-analysis-tools-are-available
>
> It looks like the OSS splint program would find that infinite loop -
> see the example here:
> http://en.wikipedia.org/wiki/Splint_%28programming_tool%29
splint certainly provides useful output. I changed my code around so
that the boundary condition would be -1 and use greater than. As splint
warns, 0 could be confusing.
I rant splint on both. In the case of the boundary condition -1
(Version 2), it warns that I am using two different types in my
compare. Very nice.
brian
// Version 1. Compare to zero
#include <stdio.h>
int main() {
int a[] = {5,6,8,3,4};
unsigned int i;
// Compares to 0
for (i= (sizeof(a) -1)/sizeof(int) ; i >= 0; i--) {
printf("%d\n",a[i]);
}
return 0;
}
br...@lamaquina:~/school/Project/practice$ splint test_loop.c
Splint 3.1.2 --- 03 May 2009
test_loop.c: (in function main)
test_loop.c:8:8: Assignment of arbitrary unsigned integral type to unsigned
int: i = (sizeof((a)) - 1) / sizeof(int)
To ignore type qualifiers in type comparisons use +ignorequals.
test_loop.c:8:40: Comparison of unsigned value involving zero: i >= 0
An unsigned value is used in a comparison with zero in a way that is either a
bug or confusing. (Use -unsignedcompare to inhibit warning)
Finished checking --- 2 code warnings
// Version 2
#include <stdio.h>
int main() {
int a[] = {5,6,8,3,4};
unsigned int i;
// Version 2. Compare to -1
for (i= (sizeof(a) -1)/sizeof(int) ; i > -1; i--) {
printf("%d\n",a[i]);
}
return 0;
}
br...@lamaquina:~/school/Project/practice$ splint test_loop.c
Splint 3.1.2 --- 03 May 2009
test_loop.c: (in function main)
test_loop.c:8:8: Assignment of arbitrary unsigned integral type to unsigned
int: i = (sizeof((a)) - 1) / sizeof(int)
To ignore type qualifiers in type comparisons use +ignorequals.
test_loop.c:8:40: Operands of > have incompatible types (unsigned int, int):
i > -1
To ignore signs in type comparisons use +ignoresigns
Finished checking --- 2 code warnings
--
Brian Lavender
http://www.brie.com/brian/
"For every complex problem there is an answer that is clear, simple, and wrong."
- H. L. Mencken
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