5.逻辑覆盖法是设计白盒测试用例的主要方法之一,通过对程序逻辑结构的遍历实现程序的覆盖。针对以下由C语言编写的程序,按要求回答问题。
int XOR(char * filename, unsigned long key){
FILE * input = NULL,*output = NULL; //1
char * outfilename = NULL;
int len = strlen(filename);
unsigned char buffer;
if( (filename[len-2] == ‘.’) && (filename[len-l] == ‘c’)){ //2,3
outfilename = new char[len+l]; //4
strcpy(outfilename,filename); outfilename[len-2] = ‘\0’;
}
else{ //5
outfilename = new char[len+5];
strcpy(outfilename , filename);
strncat(outfilename,”.c”,2);
}
input = fopen(filename,”rb”);
if( input = NULL){ //6
cout<<"Error opening file " << filename <<endl ; //7
delete [] outfilename;
outfilename = NULL;
return 1;
}
output = fopen(outfilename,”'wbf”);
if( output = NULL) { //8
cout<< "Error creating output file ”<< outfilename <<endl; //9
delete [] outfilename;
outfilename = NULL;
return 1;
}
while(! feof(input) ){ //10
if( fread(&buffer,sizeof(unsigned char), 1,input) != 1 ){ //11
if( ! feof(input)){ //12
delete [] outfilename; //13
outfllename = NULL;
fclose(input);
fclose(output);
return 1;
}
}
else{ //14
buffer A= key;
fwrite(&buffer,sizeof(unsigned char), 1,output);
}
}
fclose(input);
fclose(output);
delete [] outfllename;
return 0;
}
【问题1】(6分)
请给出满足100%DC (判定覆盖)所需的逻辑条件。
【问题2】(10分)
请画出上述程序的控制流图,并计算其控制流图的环路复杂度V(G)。
【问题3】(4分)
请给出问题2中控制流图的线性无关路径。