c语言文本输入几组三角形边长的问题答:float c;int k;void writefile(float a,float b,float c,int k){ FILE* fp;if((fp=fopen("result.txt", "a+"))==NULL) exit(0);fprintf(fp,"%f %f %f",a,b,c);switch(k){ case 5: fprintf(fp,"\t\t\t边长存在小数\n");break;case 1: fprintf(fp,"\t\t\t输入越界\n...