C 数组在传递参数数量时表现得很奇怪

Question

我正在用 C 实现命令行参数，当参数数组传递给定参数的编号时开始表现得很奇怪时，我感到震惊。这是代码:

#include <stdio.h>


int main(int a, char *arra[]){

      /*
     for(int i = 1;i<a;i++){
           printf("Arguments N%d -> %s\n",i+1,arra[i]);
      }
      printf("Totale Arguments:%d\n",a-1);

      */  

      for(int i = 0;i<=49 ;i++){
             printf("%d: -> %s\n-------------------------------------- 
             ------\n",i,arra[i]);
       }
      return 0;
 }

我的问题是数组如何访问 Linux 终端变量，例如路径变量 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

输出如下:

 0: -> ./list
--------------------------------------------
1: -> hi
--------------------------------------------
2: -> 234
--------------------------------------------
3: -> hello
--------------------------------------------
4: -> (null)
--------------------------------------------
5: -> LS_COLORS=rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arc=01;31:*.arj=01;31:*.taz=01;31:*.lha=01;31:*.lz4=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.tzo=01;31:*.t7z=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.dz=01;31:*.gz=01;31:*.lrz=01;31:*.lz=01;31:*.lzo=01;31:*.xz=01;31:*.zst=01;31:*.tzst=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.alz=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.cab=01;31:*.wim=01;31:*.swm=01;31:*.dwm=01;31:*.esd=01;31:*.jpg=01;35:*.jpeg=01;35:*.mjpg=01;35:*.mjpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.oga=00;36:*.opus=00;36:*.spx=00;36:*.xspf=00;36:
--------------------------------------------
6: -> XDG_MENU_PREFIX=gnome-
--------------------------------------------
7: -> LANG=en_US.UTF-8
--------------------------------------------
8: -> GDM_LANG=en_US.UTF-8
--------------------------------------------
9: -> DISPLAY=:1
--------------------------------------------
10: -> COLORTERM=truecolor
--------------------------------------------
11: -> USERNAME=root
--------------------------------------------
12: -> XDG_VTNR=2
--------------------------------------------
13: -> SSH_AUTH_SOCK=/run/user/0/keyring/ssh
--------------------------------------------
14: -> XDG_SESSION_ID=7
--------------------------------------------
15: -> USER=root
--------------------------------------------
16: -> DESKTOP_SESSION=gnome
--------------------------------------------
17: -> GNOME_TERMINAL_SCREEN=/org/gnome/Terminal/screen/bbdf3fc7_241a_437d_86d0_982594cbb92d
--------------------------------------------
18: -> PWD=/root/Documents/Programming/c
--------------------------------------------
19: -> HOME=/root
--------------------------------------------
20: -> SSH_AGENT_PID=1581
--------------------------------------------
21: -> QT_ACCESSIBILITY=1
--------------------------------------------
22: -> XDG_SESSION_TYPE=x11
--------------------------------------------
23: -> XDG_DATA_DIRS=/usr/share/gnome:/usr/local/share/:/usr/share/
--------------------------------------------
24: -> XDG_SESSION_DESKTOP=gnome
--------------------------------------------
25: -> GJS_DEBUG_OUTPUT=stderr
--------------------------------------------
26: -> GTK_MODULES=gail:atk-bridge
--------------------------------------------
27: -> WINDOWPATH=2
--------------------------------------------
28: -> TERM=xterm-256color
--------------------------------------------
29: -> SHELL=/bin/bash
--------------------------------------------
30: -> VTE_VERSION=5202
--------------------------------------------
31: -> XDG_CURRENT_DESKTOP=GNOME
--------------------------------------------
32: -> GPG_AGENT_INFO=/run/user/0/gnupg/S.gpg-agent:0:1
--------------------------------------------
33: -> GNOME_TERMINAL_SERVICE=:1.67
--------------------------------------------
34: -> SHLVL=1
--------------------------------------------
35: -> XDG_SEAT=seat0
--------------------------------------------
36: -> GDMSESSION=gnome
--------------------------------------------
37: -> GNOME_DESKTOP_SESSION_ID=this-is-deprecated
--------------------------------------------
38: -> LOGNAME=root
--------------------------------------------
39: -> DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/0/bus
--------------------------------------------
40: -> XDG_RUNTIME_DIR=/run/user/0
--------------------------------------------
41: -> XAUTHORITY=/run/user/0/gdm/Xauthority
--------------------------------------------
42: -> PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
--------------------------------------------
43: -> GJS_DEBUG_TOPICS=JS ERROR;JS LOG
--------------------------------------------
44: -> SESSION_MANAGER=local/FXMACO:@/tmp/.ICE-unix/1529,unix/FXMACO:/tmp/.ICE-unix/1529
--------------------------------------------
45: -> _=./list
--------------------------------------------
46: -> OLDPWD=/root/Documents/Books
--------------------------------------------
47: -> (null)
--------------------------------------------
Segmentation fault

Answer 1

for(int i = 0;i<=49 ;i++){

正如我们在这里看到的，您的参数列表少于 50 个元素

最好使用标准名称并考虑传递的参数数量(这就是 argc 的原因)

int main(int argc char *argv[])
{

    for(int i = 0;i < argc ;i++){