Differences

This shows you the differences between two versions of the page.

--- soft:c [2020/07/24 08:23] – Ce Zhang
+++ soft:c [2020/11/05 02:10] (current) – Ce Zhang
@@ Line 1: / Line 1: @@
-====C++====
+=====C++=====
-===Read===
-''Monospaced Text''
+==== 2D array ====
+<code>
+TGraph*** g = new TGraph**[Nfile];
+for(i loop) g[i] = new TGraph*[t[i]->Nentries];
+for(int j = 0; j<t[i]->Nentries;j++) g[i][j] = ...(TGraph *)...
+</code>
-#include <fstream>
+====EOF====
-  * ofstream        create, write into new file
+<code>
-  * ifstream         read the existing file
+<<EOF        //开始
-  * fstream          read & write
+....
+EOF            //结束
+//将一个文件的内容输出到另一个文件中：
+# cat fileA > fileB
+//将"<< EOF EOF"替代输入对象文件fileA：
+# cat << EOF > fileB
+//命令执行后，提示用户输入内容，输入结束后，用户的输入内容被保存到了fileB中。
+</code>
+====I/O====
 <code>
@@ Line 16: / Line 30: @@
        {
             out << "This is a line.\n";
-            out << "This is another line.\n";
             out.close();
+        }
+      return 0;
+ // reading a text file
+    #include <iostream.h>
+    #include <fstream.h>
+    #include <stdlib.h>
+    int main () {
+        char buffer[256];
+        ifstream in("test.txt");
+        if (! in.is_open())
+        { cout << "Error opening file"; exit (1); }
+        while (!in.eof() )
+        {
+            in.getline (buffer,100);
+            cout << buffer << endl;
         }
         return 0;
@@ Line 23: / Line 53: @@
 </code>
+<code>
+std::vector<char> v;
+	if (FILE *fp = fopen("filename", "r"))
+	{
+		char buf[1024];
+		while (size_t len = fread(buf, 1, sizeof(buf), fp))
+			v.insert(v.end(), buf, buf + len);
+		fclose(fp);
+	}
+</code>
+====将变量名替换为字符串====
+<code>
+#define name2str(name) (#name)
+</code>
+<code>
+#define xstr(s) str(s)
+#define str(s) #s
+#define foo 4
+     str (foo)
+          ==> "foo"
+     xstr (foo)
+          ==> xstr (4)
+          ==> str (4)
+          ==> "4"
+ </code>
+====函数指针作为参数====
+<code>
+void DiffusionModel (bool (*GeometryFunction)(double, double, double)) )
+bool InsideAerogel(double x, double y, double z);
+DiffusionModel(
+    InsideAerogel
+);
+</code>
+====char * 转换 (for input arg.)====
+<code>
+//char* to int
+int a = stoi(argv[1]);
+//char* 转 float/double
+float b = stof(argv[2]);
+double bb = stod(argv[2]);
+//char* 转 string (可以直接转）
+string str = argv[3];
+cout << a << endl << b << endl << bb << endl << str << endl;
+</code>