c - How can a single printf statement changes value in an array? -


the following program prints prime numbers between 1 , 10.

#include <stdio.h> int* prime(int x,int y,int* range);  void main() {     int *x,s=10;     int i=0;      x=prime(1,10,&s);      for(i=0;i<s;i++)     {         printf("%d\n",x[i]);     }   } int* prime(int x,int y,int *range){      int num[100],i,j,flag,inc=0;      for(i=x;i<=y;i++)     {         flag=1;         for(j=2;j<=(i/2);j++)         {             if(i%j == 0)                 flag=-1;         }          if(flag==1)         {              num[inc]=i;             inc++;         }      }     *range=inc;     //printf("$$%d$$",*range);     return num; }

the output 1 2 3 5 0 in above case, if remove the comment in printf statement in prime function , give normal printf statement output 1 2 3 5 7 how possible?? what's bug here??

the compiler used gcc compiler in linux platform.

your prime() method returns local variable num sitting on stack, it's not in scope (aka invalid) after theprime() call returns.

a couple of fixes:

  • you might able make num static in prime
  • you dynamically allocate num (remember free it)
  • you pass num prime method.

Comments

Post a Comment

Popular posts from this blog

basic authentication with http post params android -

i doing basic authentication passing username , password , using basicnamevaluepair sending post params response service. my method: public stringbuilder callservicehttppost(string username, string password, string type) { // create new httpclient , post header httpclient httpclient = new defaulthttpclient(); httppost httppost = new httppost(webservice + type); httpresponse response = null; stringbuilder total = new stringbuilder(); try { url url = new url(webservice + type); /*string base64encodedcredentials = base64.encodetostring((username + ":" + password).getbytes(), base64.url_safe | base64.no_wrap);*/ string base64encodedcredentials = "basic " + base64.encodetostring( (username + ":" + password).getbytes(), base64.no_wrap); httppost.setheader("auth...
Read more

vb.net - Virtual Keyboard commands -

i wondering difference between virtual these keyboard commands is: keyeventf_extendedkey , keyeventf_keyup is. everywhere have looked gives me description based off integers , not want know each of them does. you've tagged question vb.net, these have nothing @ vb.net. they're constants defined in windows header files, use win32 api functions. as far difference, can't tell looking @ values. individual values not particularly important, that's why named identifiers used. what's important used , documentation functions tells mean. the first one, keyeventf_extendedkey , used keybdinput structure (which used along e.g. sendinput function) pass information synthesized keyboard input. if flag used, means scan code should interpreted extended key. technically, means scan code preceded prefix byte value 224 (&he0 in hexadecimal notation). the second one, keyeventf_keyup , 1 of flags available use structure. means key being released (going up)...
Read more

c++ - End of file on pipe magic during open -

i have c++ application in starting process(wireshark) following. if (fp == null){ fp = popen(processpath, "r"); //processpath process want start if (!fp){ throw std::invalid_argument("cannot start process"); } fprintf(fp, d_msg);//d_msg input want provide process } else if(fp != null){ fprintf(fp, d_msg); } the problem when execute c++ application, start wireshark error end of file on pipe magic during open what should avoid that? also tried using mkfifo create named pipe , execute it. used this: if (fp == null){ system("mkfifo /tmp/mine.pcap"); fp = popen("wireshark -k -i /tmp/mine.pcap", "r"); if (!fp){ dout << "cannot start wireshark"<<std::endl; throw std::invalid_argument("cannot start wireshark"); } input = fopen("/tmp/mine.pcap", "wb"); fprintf(input , d_msg); fclose(input)...
Read more