[英]How to pass character array to a function in C++ without any temporary char array as variable?
[英]C++ How to pass a variable char array from one function to another
我有一個問題,關於將一個字符數組的變量從一個函數傳遞到下一個函數。
以下是涉及的代碼示例:
int main( int argc, char** argv )
{
int value = 0;
int nCounter = 0;
FILE* fIn = NULL;
char * sLine = new char[MAX_FILENAME_SIZE];
char * sFileName = new char [MAX_FILENAME_SIZE];
char * s = new char [MAX_FILENAME_SIZE];
if ((fIn = fopen(ImgListFileName,"rt"))==NULL)
{
printf("Failed to open file: %s\n",ImgListFileName);
return nCounter;
}
while(!feof(fIn)){
//set the variables to 0
memset(sLine,0,MAX_FILENAME_SIZE*sizeof(char));
memset(sFileName,0,MAX_FILENAME_SIZE*sizeof(char));
memset(s,0,MAX_FILENAME_SIZE*sizeof(char));
//read one line (one image filename)
//sLine will contain one line from the text file
fgets(sLine,MAX_FILENAME_SIZE,fIn);
//copy the filename into variable s
strncpy(s, sLine, strlen(sLine)-1);
//put a \0 character at the end of the filename
strcat(sLine,"\0");
//create the filename
strcat(sFileName,s);
nCounter++;
fclose(fIn);
delete sLine;
delete sFileName;
delete s;
const int size = 60;
char path[size] = "path";
strcat(path,sFileName);
printf (path);
IplImage *img = cvLoadImage(path);
detect_and_draw(img);
cvWaitKey();
cvReleaseImage(&img);
cvDestroyWindow("result");
void detect_and_draw( IplImage* img )
{
More code that isn't involved....
cvSaveImage(sFileName, img);
現在,我嘗試了以下方法:
void getFilename(char * sFileName)
{
printf("The filename is %s\n", sFileName);
return;
}
然后致電
char * S ="string"
getFilename(S);
cvSaveImage(S,img);
但是“字符串”被放置在“文件名是:字符串”中。
我該怎么做才能在cvSaveImage(sFileName,img)中使用char數組sFileName?
在此先感謝您,如果您需要任何進一步的說明,請詢問!
忽略未定義的行為,不必要的動態分配等,您似乎想完成的事情歸結為以下一般順序:
std::string path;
while (std::getline(fIn, path)) {
std::cout << "path: " << path;
IplImage *img = cvLoadImage(path.c_str());
detect_and_draw(img, path);
cvWaitKey();
cvReleaseImage(&img);
cvDestroyWindow("result");
}
void detect_and_draw(IpImage *img, std::string const &path) {
// ...
cvSaveImage(path.c_str(), img);
}
我想我做的事情與此有所不同-可能從Image
類開始,例如:
class Image {
IpImage *img;
std::string path;
public:
Image(std::string const &name) :
img(cvLoadImage(name.c_str()), path(name)
{ }
~Image() { cvReleaseImage(&img); }
void detect_and_draw() {
// ...
cvSaveImage(path);
}
};
使用它,您的代碼將更像這樣:
while (std::getline(fIn, path)) {
Image img(path);
img.detect_and_draw();
cvWaitKey();
cvDestroyWindow("result");
}
尚不完全清楚,但是cvDestroyWindow
聽起來也很像真正屬於析構函數的東西,但是我不確定這些部分如何組合在一起以確保析構函數是什么-也許是Image
,更可能是其他東西。
我會注意到, detect_and_draw
實際上尖叫“此代碼忽略了單一責任原則”。 它在名稱中列出了兩個職責,並且似乎也至少有三分之一(保存文件)。
如果我的理解正確,那么您遇到的是一個范圍界定問題。 您基本上有:
int main(/* */)
{ char sFileName[MAX_FILENAME_SIZE];
/* code to initialize sFileName to contain a value */
detect_and_draw(img);
}
void detect_and_draw(IplImage *img)
{ cvSaveImage(sFileName, img);
}
問題在於sFileName
對於main()
是本地的,而在detect_and_draw()
不可訪問。 您可以修改detect_and_draw()
以采用第二個參數:
int main()
{ /* stuff */
detect_and_draw(img, sFileName);
}
void detect_and_draw(IplImage *img, const char* fn)
{ cvSaveImage(fn, img);
}
或將sFileName設為在main()
范圍之外聲明/定義的全局變量-盡管通常將其視為劣等解決方案。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.