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Purpose of Unions in C and C++
... @legends2k: any decent optimizer will recognize bitwise operations that select an entire byte and generate code to read/write the byte, same as the union but well-defined (and portable). e.g. uint8_t getRed() const { return colour & 0x000000FF; } void setRed(uint8_t r) { colour = (colour &...
Read Excel File in Python
...ues for a given column
values = df['Arm_id'].values
#get a data frame with selected columns
FORMAT = ['Arm_id', 'DSPName', 'Pincode']
df_selected = df[FORMAT]
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How to split a string with any whitespace chars as delimiters
...lit() to split a String into an Array of substrings using all whitespace characters ( ' ' , '\t' , '\n' , etc.) as delimiters?
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Entity framework self referencing loop detected [duplicate]
...anonymous type with the props you want
example (psuedo)code:
departments.select(dep => new {
dep.Id,
Employee = new {
dep.Employee.Id, dep.Employee.Name
}
});
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Tools to get a pictorial function call graph of code [closed]
...that contains a lot of interesting performance data.
On the bottom right, select the "Call graph" tab. This shows an interactive call graph that correlates to performance metrics in other windows as you click the functions.
To export the graph, right click it and select "Export Graph". The exporte...
memcpy() vs memmove()
...or you risk undefined behaviour, while the memory in memmove can overlap.
char a[16];
char b[16];
memcpy(a,b,16); // valid
memmove(a,b,16); // Also valid, but slower than memcpy.
memcpy(&a[0], &a[1],10); // Not valid since it overlaps.
memmove(&a[0], &a[1],10); ...
Will using 'var' affect performance?
... answered Nov 18 '09 at 14:42
RichardODRichardOD
27.4k88 gold badges5454 silver badges7676 bronze badges
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Maximum number of records in a MySQL database table
...g with multiple billions of entries? (which would probably just make your select statements melt down long before then)
– Kzqai
Apr 26 '10 at 19:35
2
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An efficient compression algorithm for short text strings [closed]
...tion you should ask is "what algorithm to compress text strings with these characteristics". For instance, if long repetitions are expected, simple Run-Lengh Encoding might be enough. If you can guarantee that only English words, spaces, punctiation and the occasional digits will be present, then Hu...
How to throw std::exceptions with variable messages?
...ptions can be constructed from a std::string:
#include <stdexcept>
char const * configfile = "hardcode.cfg";
std::string const anotherfile = get_file();
throw std::runtime_error(std::string("Failed: ") + configfile);
throw std::runtime_error("Error: " + anotherfile);
Note that the base cl...