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Executing multi-line statements in the one-line command-line?
...rt sys
for r in range(3): print 'rob'
EOF
in latter case leading tab characters are removed too (and some structured outlook can be achieved)
instead of EOF can stand any marker word not appearing in the here document at a beginning of a line (see also here documents in the bash manpage or he...
Is it better in C++ to pass by value or pass by constant reference?
...ractice1 to use pass by const ref for all types, except for builtin types (char, int, double, etc.), for iterators and for function objects (lambdas, classes deriving from std::*_function).
This was especially true before the existence of move semantics. The reason is simple: if you passed by value...
Difference between class and type
...y, how you can interact with it.
Examples of primitive types:
int
float
char
boolean
Examples of class types:
String
Integer
Boolean
ArrayList
StringBuilder
Examples of interface types:
Collection
List
Map
Serializable
Examples of array types:
int[]
String[]
Integer[][][]
Basically,...
Is cout synchronized/thread-safe?
...cent version of MSVC (currently for VS 2010/MSVC 10/cl.exe 16.x). You can select the information for older versions of MSVC using a dropdown control on the page (and the information is different for older versions).
share
...
How to track down a “double free or corruption” error
...debug it.
#include<stdio.h>
#include<stdlib.h>
int main()
{
char *x = malloc(100);
free(x);
free(x);
return 0;
}
[sand@PS-CNTOS-64-S11 testbox]$ vim t1.c
[sand@PS-CNTOS-64-S11 testbox]$ cc -g t1.c -o t1
[sand@PS-CNTOS-64-S11 testbox]$ ./t1
*** glibc detected *** ./t1: double free ...
Which, if any, C++ compilers do tail-recursion optimization?
...t for program correctness.
#include <stdio.h>
static int atoi(const char *str, int n)
{
if (str == 0 || *str == 0)
return n;
return atoi(str+1, n*10 + *str-'0');
}
int main(int argc, char **argv)
{
for (int i = 1; i != argc; ++i)
printf("%s -> %d\n", argv[i], at...
What does “zend_mm_heap corrupted” mean
...#include <stdlib.h>
int main(void) {
void **mem = malloc(sizeof(char)*3);
void *ptr;
/* read past end */
ptr = (char*) mem[5];
/* write past end */
memcpy(mem[5], "whatever", sizeof("whatever"));
/* free invalid pointer */
free((void*) mem[3]);
retur...
Who architected / designed C++'s IOStreams, and would it still be considered well-designed by today'
...; operator will only read from the stream until it encounters a whitespace character, since there's no length information stored in the stream. So even though we output a string object containing "hello world", we're only going to input a string object containing "hello". So while the stream has s...
What is “Argument-Dependent Lookup” (aka ADL, or “Koenig Lookup”)?
...eems a bit backwards. I would expect the problem do be when std::swap() is selected rather than the overload specific to the type, A::swap(). The example with std::swap(A::MyClass&, A::MyClass&) seems misleading. since std would never have a specific overload for a user type, I don't think i...
Are the shift operators () arithmetic or logical in C?
... of i, after integer promotion, be T. Assuming n to be in [0, sizeof(i) * CHAR_BIT) — undefined otherwise — we've these cases:
| Direction | Type | Value (i) | Result |
| ---------- | -------- | --------- | ------------------------ |
| Right (>>) | unsigned | ≥...