论述题： 已知C源程序如下： /**************************
问题：
论述题： 已知C源程序如下： /**************************************************/ /* 功能：检查输入的标识符是否符合C语言规则 */ /**************************************************/ #include＜stdio.h＞ #include＜string.h＞ #include＜ctype.h＞ #include＜conio.h＞ #include＜malloc.h＞ char*IsLegal(char*CheckWord); const int MaxWordLen=32; char*ErrorMessages[]={ /*错误信息列表*/ "合法!"， "首字符只能是字母或下划线!"， "常、变量只能由字母、下划线和数字构成!"， "常、变量标识不能用C语言关键字!"。 "常、变量标识不能用C语言预定义函数名!"， "内存不够!" }; int main() { char*Prompt="C语言标识符的命名要遵守以下原则："; char*TestWord; int i; TestWord=(char*)malloc(sizeof(char)*MaxWordLen); /*TestWord存放用户输入*/ if(!TestWord) return 1; /*显示部分提示信息*/ puts(Prompt); for(i=1;i＜=4；i++){ puts(ErrorMessages[i]); } while(1){ printf("\n\n请输入一个标识符(大写的Q退出):");/*提示*/ scanf("%s",TestWord); /*得到用户输入*/ if(toupper)(TestWord[0]))==’0’) break; /*循环出口*/ prind("\n%s %s",TestWord,IsLegal(TestWord));/*判定标识符的合法性*/ } free(TesfWord); return 0; } /*此函数检验标识符命名的合法性*/ char*IsLegal(ehar*CheckWord) { char*KeyWords[]={"auto","break","case","char","continue","const","default", "do","double","else","enum",extern","float","for","goto", "if","int","long","noalias","register","return","short", "signed","sizeof","static","struct","switch","typedef", "union","unsigned","void","volatile","while","defined", "define","undef","include","ifdef","ifndef","endif","line", "error","elif","pragma"}; /*C关键字列表*/ char*Functions[]={"close","crest","eof","fclose","fcloseall","feof","fopen", "ferror","fgetchar","fgets","fprintf","fputc","fputchar", "fseek","get","putch","putc","printf","open","putchar", "puts","read","scanf","abs","acos","asin","math","atan", "atan2","atof","atoi","atol","ceil","dos","cosh",ecvt", "exp","fabs","floor","fmod","frexp","itoa","labs","ldexp", "log","log10","modf","pow","rand","sin","sqrt","srand", "strtod","strlol","tan","tanh","ultoa","memset","strcpy", "strcat","strchr","strcrap","calloc","isalnum","isalpha", "toascii","tolower","tollpper","exit"); /*C主要预定义函数列表*/ char*Others="_"; /*’_’也可以用于关键字，但我们不推荐您使用!*/ int WordLength,i; char*WordTemp; WordLength=strlen(CheckWord); /*检查标识符命名原则1*/ if((isalpha(CheckWord[0])==0)&&(CheckWord[0]!=Others[0])) return ErrorMessages[1]; /*检查标识符命名原则2*/ for(i=0;i＜WordLength;i++) if((isalnum(CheekWord[i]==0)&&(CheckWord[i]!=Others[0])) return ErrorMessages[2]; /*检查标识符命名原则3*/ for(i=0;i＜44;i++) { if(!strcmp(CheckWord,KeyWords[i])) return ErrorMessages[3]; } /*检查标识符命名原则4 */ for(i=0;i＜69;i++) { if(!stremp(CheckWord,Functions[i])) return ErrorMessages[4]; } return ErrorMessages[0]; }
参照QESAT/C软件分析与测试工具的规定，画出程序中所有函数的控制流程图；