C array of three ints C++ vector of three ints in Java Writer PDF 417 in Java C array of three ints C++ vector of three ints

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C array of three ints C++ vector of three ints using j2ee tobuild pdf417 with web,windows application WinForms 10 Debugging When you debug code tha t has these two declarations, you can find out what you are looking at by using the whatis command:. (gdb) whatis myarray ty PDF417 for Java pe = int [3] Size is fixed. (gdb) whatis myvector type = std::vector<int,std::allocator<int> > Size is dynamic not reported..

All C++ containers have a size method that tells you how many elements are stored in the container. You can call this method from gdb just like any other function:. (gdb) p myvector.size() $1 = 3 There is a catch, howev er: C++ templates do not generate code unless the code is used (instantiated). So unless your code actually uses the size method above, it will not be instantiated, and there will be no size method in the executable to call. In this case, you might see a message like the following:.

(gdb) p myvector.size() Cannot evaluate function -- may be inlined To make matters more co nfusing, the method could get instantiated indirectly by using other methods. So you might be able to use this technique to debug in one program but not another. To make your life easier, you can consciously add superfluous method calls to your code for the purpose of debugging.

Also note that instantiation must be done for each unique type, so instantiating vector<int>::size does not instantiate vector<float>::size. Note that gdb is able to treat containers of std::vector as regular arrays, so most syntax that works with arrays also works with vectors. Most other containers require help from method calls and iterators.

Recall that an iterator is the C++ equivalent of a pointer used to access data in containers. Iterators use the same syntax as pointers, but they are not pointers. Luckily, gdb understands iterators, so you can print data using equivalent syntax.

Consider the following code fragment:. std::list<int> my PDF417 for Java list; ...

std::list<int>::iterator x = mylist.begin();. Getting Comfortable with the GNU Debugger: gdb When x is instantiated pdf417 2d barcode for Java inside the code, you can print use the same syntax with this iterator as you would with a pointer inside gdb:. (gdb) p *x $1 = (int &) @0x804c1f8: 100. That s about as much as spring framework barcode pdf417 you can do with an iterator inside gdb. You cannot use pointer math or walk through a sequence container by using the ++ operator in gdb. If you need to see data inside C++ containers (other than a vector) from gdb, you will need to add some code to facilitate this.

The display Command display prints the specified expression each time the program stops. You can display as many expressions as you want and format each expression using the same syntax as the x command. Compile and run the program in Listing 10-5 with gdb.

This program also demonstrates using gdb with containers.. LISTING 10-5. 1 2 3 4 5 6 7 8 9 10 11 spring framework PDF417 12 13 14 15 16 17 18. permute.cpp: A C++ Program to Demonstrate gdb s display Command #include <stdio.h> jdk pdf417 2d barcode ; #include <string> #include <algorithm> int main(int argc, char *argv[]) { int i = 0; std::string token = "ABCD"; // Simple loop goes through every permutation of a string // using std::next_permutation. do { i++; } while (std::next_permutation(token.

begin(), token.end())); printf("%d permutations\n", i); return 0; }. 10 Debugging token is a four-charact Java barcode pdf417 er string that this program permutes rithm std::next_permutation. The laws of combinatorics. using the C++ algostate s that there are four factorial6 (4!) permutations of this string. You set a breakpoint on line 13 so you can watch what it does with the display command:. Breakpoint 2, main (arg pdf417 2d barcode for Java c=1, argv=0xbffce1a4) at permute.cpp:13 13 i++; (gdb) display/xw token.c_str() Display four chars as a longword.

1: x/xw token.c_str () 0x804a014: 0x44434241 (gdb) display/s token.c_str() Display same thing as ASCII.

2: x/s token.c_str () 0x804a014: "ABCD" (gdb) cont Continuing. Breakpoint 2, main (argc=1, argv=0xbffce1a4) at permute.

cpp:13 13 i++; 2: x/s token.c_str () 0x804a014: "ABDC" 1: x/xw token.c_str () 0x804a014: 0x43444241 No need to retype cont.

(gdb) Continuing. Breakpoint 2, main (argc=1, argv=0xbffce1a4) at permute.cpp:13 13 i++; 2: x/s token.

c_str () 0x804a014: "ACBD" 1: x/xw token.c_str () 0x804a014: 0x44424341.
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