5.2.1命令行参数 - 命令行参数5.2

5.10Command-lineArgumentsInenvironmentsthatsupportC,thereisawaytopasscommand-lineargumentsorparameterstoaprogramwhenitbeginsexecuting.Example: /*echocommand-linearguments:1stversion*/ main(intargc,char*argv[]) { inti; for(i=1;i<argc;i++) printf(“%s%s”,argv[i],(i<argc-1)?””:””); printf(“\n”); return0; } /*echocommand-linearguments:2ndversion*/ main(intargc,char*argv[]) { while(--argc>0) printf(“%s%s”,*++argv,(argc>1)?““:””); printf(“\n”); return0; }5.10Command-lineArgumentsexample2: #include<stdio.h> #include<string.h> #defineMAXLINE1000 intgetline(char*line,intmax);

/*find:printlinesthatmatchpatternfrom1starg*/ main(intargc,char*argv[]) { charline[MAXLINE]; intfound=0; if(argc!=2)printf(“Usage:findpattern\n”); elsewhile(getline(line,MAXLINE)>0) if(strstr(line,argv[1])!=NULL){ printf(“%s”,line); found++; } returnfound; }5.10Command-lineArgumentsexample3: find–x–npatternx:execpt,n:printlinenumber #include<stdio.h> #include<string.h> #defineMAXLINE1000 /*find:printlinesthatmatchpatternfromistarg*/5.10Command-lineArguments main(intargc,char*argv[]) { charline[MAXLINE]; longlineno=0; intc,execpt=0,number=0,found=0; while(--argc>0&&(*++argv)[0]==‘-’)while(c=*++argv[0]) switch(c){ case‘x’:execpt=1;break; case‘n’:number=1;break; default: printf(“find:illegaloption%c\n”,c); argc=0;found=-1;break; } if(argc!=1)printf(“Usage:find–x–npattern\n”); else…5.10Command-lineArguments…while(getline(line,MAXLINE)>0){ lineno++; if((strstr(line,*argv)!=NULL)!=execpt){