Command Line Argument processing in c

Question

On running the below code, it stucks after displaying the argv[0], argv[1] and argv[2] line. Further flow of code is blocked at this point, can any one help why it is stopping its execution or is it entering into an infinite loop.

#include <stdio.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <string.h> #include <stdlib.h> #include "p8log.h" #include <errno.h> int main(int argc, char* argv[]) { char* PORT; char* IPADDR; printf("Arg Count=%d\n",argc); printf("Arguments are=%s,%s,%s\n",argv[0],argv[1],argv[2]); printf("HELLO"); PORT=argv[1], printf("WORLD"); IPADDR=argv[2]; printf("START"); printf("port num=%s",PORT); printf("IP ADDR=%s",IPADDR); printf("END"); /* some algorithm of calculation */ return 0; }

Execution

./file-exe 11111 127.0.0.1

Output

Arg Count=3 Arguments are=./file-exe,11111,127.0.0.1

The title is C++ but the tag is C. Which language do you use? — MikeCAT
– MikeCAT, Commented Mar 3, 2016 at 7:11
Apparently there is no control of flow; it is unlikely that the shown code causes an infinite loop. What is the output so far? Is the part where END is written to the output ever reached? — Codor
– Codor, Commented Mar 3, 2016 at 7:13
Add \n to all printf's. Post the input you enter, then the output you see. — dxiv
– dxiv, Commented Mar 3, 2016 at 7:16
For me it works fine: $ ./a.exe 11111 127.0.0.1 Arg Count=3 Arguments are=C:\tmp\a.exe,11111,127.0.0.1 HELLOWORLDSTARTport num=11111IP ADDR=127.0.0.1END — Kirill
– Kirill, Commented Mar 3, 2016 at 7:23
P.S. After the OP edit, crystal ball says it's stuck in the /* some algorithm of calculation */ code that was not posted. — dxiv
– dxiv, Commented Mar 3, 2016 at 7:23

Preston Garrison · Accepted Answer · 2016-03-03 07:29:32Z

fflush(NULL); is good to do after any output, if you want to make sure it prints to screen. printf is buffered, so it can get lost.

./a.out 11111 127.0.0.1 Arg Count=3 Arguments are=./a.out,11111,127.0.0.1 HELLO WORLD START port num=11111 IP ADDR=127.0.0.1 END

works fine, you needed some \n to break up lines, like so..

#include <stdio.h> #include <string.h> #include <stdlib.h> int main(int argc, char* argv[]) { char* PORT; char* IPADDR; printf("Arg Count=%d\n",argc); printf("Arguments are=%s,%s,%s\n",argv[0],argv[1],argv[2]); printf("HELLO\n"); PORT=argv[1], printf("WORLD\n"); IPADDR=argv[2]; printf("START\n"); printf("port num=%s\n",PORT); printf("IP ADDR=%s\n",IPADDR); printf("END\n"); fflush(NULL); /* some algorithm of calculation */ return 0; }

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