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将文件中的c风格的注释转换为c++风格的注释，并保存在另一个文件中

思路：（有限自动机）

图解：一般情况

#include
   
    #pragma warning(disable:4996)typedef enum condition{//状态定义	NOT_ANNOTATION,//不是注释	MAYBE_IN_ANNOTATION,//可能进入注释	C_ANNOTATION,//C风格注释	CPP_ANNOTATION,//C++风格注释	MAYBE_OUT_ANNOTATION//可能出注释}Condition;int main(){	FILE *pIn = fopen("input.c", "rt");	if (pIn == NULL){		perror("fopen test");		return 1;	}	FILE *pOut = fopen("output.c", "wt");	if (pOut == NULL){		fclose(pIn);		perror("fopen out");		return 1;	}	char ch;	Condition state = NOT_ANNOTATION;	do{		ch = fgetc(pIn);		switch (state)		{		case NOT_ANNOTATION:		{			if (ch == '/'){				state = MAYBE_IN_ANNOTATION;				fputc(ch, pOut);			}			else{				state = NOT_ANNOTATION;				fputc(ch, pOut);			}			break;		}		case MAYBE_IN_ANNOTATION:		{			if (ch == '/'){				state = CPP_ANNOTATION;				fputc(ch, pOut);			}			else if (ch == '*'){				state = C_ANNOTATION;				fputc('/', pOut);			}			else{				state = NOT_ANNOTATION;				fputc(ch, pOut);			}			break;		}		case CPP_ANNOTATION:		{			if (ch == '\n'){				state = NOT_ANNOTATION;				fputc(ch, pOut);			}			else{				fputc(ch, pOut);			}			break;		}		case C_ANNOTATION:		{			if (ch == '*'){				state = MAYBE_OUT_ANNOTATION;			}			else{				fputc(ch, pOut);				if (ch == '\n'){					fprintf(pOut, "//");				}			}			break;		}		case MAYBE_OUT_ANNOTATION:		{			if (ch == '*'){				state = MAYBE_OUT_ANNOTATION;				fputc(ch, pOut);			}			else if (ch == '/'){				char nextch = fgetc(pIn);//向前看一个字符				if (nextch != '\n'){					fputc('\n', pOut);//做出判断				}				ungetc(nextch, pIn);//将看的字符放回所读的缓冲区中				state = NOT_ANNOTATION;			}			else{				state = C_ANNOTATION;				fputc('*', pOut);				fputc(ch, pOut);			}			break;		}		}	} while (ch != EOF);	fclose(pOut);	fclose(pIn);	return 0;}
   

运行结果：