Demonstrate pointer usage

 /* <Br/> the following example demonstrates that the pointer corresponds to the address. When the address content is changed, the pointer content also changes <br/> */<br/> # include <winsock2.h> <br/> # include <stdio. h> <br/> # include <stdio. h> <br/> # include <sys/timeb. h> <br/> # include <time. h> </P> <p> int evutil_gettimeofday (struct timeval * TV, struct timezone * tz) <br/>{< br/> struct _ timeb TB; </P> <p> If (TV = NULL) <br/> return-1; </P> <p> _ ftime (& TB ); <br/> TV-> TV _sec = (long) TB. time; <br/> TV-> TV _usec = (INT) TB. millitm) * 1000; <br/> return 0; <br/>}</P> <p> # define evutil_timeradd (TVP, UVP, vvp) /<br/> do {/<br/> (vvp)-> TV _sec = (TVP)-> TV _sec + (UVP)-> TV _sec; /<br/> (vvp)-> TV _usec = (TVP)-> TV _usec + (UVP)-> TV _usec;/<br/> If (vvp) -> TV _usec> = 1000000) {/<br/> (vvp)-> TV _sec ++;/<br/> (vvp)-> TV _usec-= 1000000; /<br/>}/ <br/>} while (0) <br/> # defineevutil_timersub (TVP, UVP, vvp) /<br/> do {/<br/> (vvp)-> TV _sec = (TVP)-> TV _sec-(UVP)-> TV _sec; /<br/> (vvp)-> TV _usec = (TVP)-> TV _usec-(UVP)-> TV _usec;/<br/> If (vvp) -> TV _usec <0) {/<br/> (vvp)-> TV _sec --;/<br/> (vvp)-> TV _usec + = 1000000; /<br/>}/ <br/>} while (0) <br/> # defineevutil_timerclear (TVP)-> TV _sec = (TVP) -> TV _usec = 0 </P> <p> int main (INT argc, char * argv []) <br/>{< br/> struct timeval TV; <br/> struct timeval * TV _p; </P> <p> evutil_gettimeofday (& TV, null); </P> <p> TV _p = & TV; </P> <p> printf ("current time is: % s/n", ctime (& TV _p-> TV _sec )); <br/> // assign the address to the pointer </P> <p> struct timeval TVM; <br/> TVM. TV _sec = 10; <br/> TVM. TV _usec = 0; <br/> // increase the TV time <br/> evutil_timeradd (& TV, & TVM, TV _p ); </P> <p> printf ("after add 10 second is: % S/R/N", ctime (& TV _p-> TV _sec )); </P> <p> return 0; <br/>}</P> <p>