why( warning: left-hand operand of comma expression has no effect)

SmallAnt unixant at gmail.com
Fri Nov 16 12:57:31 CET 2012


i embed libev in my program,when compile,there are warnings:
///
./libev/ev_poll.c: In function `poll_poll':
./libev/ev_poll.c:110: warning: left-hand operand of comma expression
has no effect
In file included from ohc_ev.c:7:
./libev/ev.c: In function `verify_watcher':
./libev/ev.c:2504: warning: left-hand operand of comma expression has no effect
./libev/ev.c:2507: warning: left-hand operand of comma expression has no effect
./libev/ev.c: In function `verify_heap':
./libev/ev.c:2517: warning: left-hand operand of comma expression has no effect
./libev/ev.c:2518: warning: left-hand operand of comma expression has no effect
./libev/ev.c:2519: warning: left-hand operand of comma expression has no effect
./libev/ev.c: In function `array_verify':
./libev/ev.c:2530: warning: left-hand operand of comma expression has no effect
./libev/ev.c: In function `ev_verify':
./libev/ev.c:2548: warning: left-hand operand of comma expression has no effect
./libev/ev.c:2555: warning: left-hand operand of comma expression has no effect
./libev/ev.c:2556: warning: left-hand operand of comma expression has no effect
./libev/ev.c: In function `timers_reify':
./libev/ev.c:2733: warning: left-hand operand of comma expression has no effect
./libev/ev.c: In function `periodics_reify':
./libev/ev.c:2797: warning: left-hand operand of comma expression has no effect
./libev/ev.c:2784: warning: unused variable `feed_count'
./libev/ev.c: In function `ev_run':
./libev/ev.c:2936: warning: left-hand operand of comma expression has no effect
./libev/ev.c:3056: warning: left-hand operand of comma expression has no effect
./libev/ev.c: In function `ev_io_start':
./libev/ev.c:3228: warning: left-hand operand of comma expression has no effect
./libev/ev.c:3229: warning: left-hand operand of comma expression has no effect
./libev/ev.c:3237: warning: suggest parentheses around arithmetic in
operand of |
./libev/ev.c: In function `ev_io_stop':
./libev/ev.c:3250: warning: left-hand operand of comma expression has no effect
./libev/ev.c: In function `ev_timer_start':
./libev/ev.c:3270: warning: left-hand operand of comma expression has no effect
./libev/ev.c: In function `ev_timer_stop':
./libev/ev.c:3298: warning: left-hand operand of comma expression has no effect
./libev/ev.c: In function `ev_periodic_start':
./libev/ev.c:3360: warning: left-hand operand of comma expression has no effect
./libev/ev.c: In function `ev_periodic_stop':
./libev/ev.c:3392: warning: left-hand operand of comma expression has no effect
./libev/ev.c: In function `ev_signal_start':
./libev/ev.c:3429: warning: left-hand operand of comma expression has no effect
./libev/ev.c:3432: warning: left-hand operand of comma expression has no effect
./libev/ev.c: In function `ev_child_start':
./libev/ev.c:3549: warning: left-hand operand of comma expression has no effect
./libev/ev.c: In function `ev_embed_start':
./libev/ev.c:4119: warning: left-hand operand of comma expression has no effect
./libev/ev.c:4468:27: warning: "/*" within comment
./libev/ev.c:4469:27: warning: "/*" within comment
ohc_ev.c: At top level:
./libev/ev.c:1619: warning: 'fd_rearm_all' defined but not used

////
could someone tell me why??

uname -s : 2.6.9_5-9-0-0
gcc:gcc version 3.4.5 20051201 (Red Hat 3.4.5-2)



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