C create string of text and variables

Question

I m trying to do something very simple and yet  after an hour of so of searching a I can t find a suitable answer so I must be missing something fairly obvious   I m trying to dynamically create filenames for use with ifstream  Whilst I understand various methods are available of doing this  I have settled on creating a std  string  and the using stringname c str to convert to const   The problem is however that I need to create the string with a mix of variables and predefined text values  I m getting compiler errors  so this must be a syntax issue   Pseudo   std  string var    sometext    somevar    sometext    somevar    Thanks

User · Answer

The new way to do with c  20 is using format    include  lt format gt   auto var   std  format  sometext    sometext      somevar  somevar

User · Answer

See also boost  format    include  lt boost format hpp gt   std  string var    boost  format  somtext  s sometext  s     somevar   somevar  str

User · Answer

std  string var    sometext    somevar    sometext    somevar    This doesn t work because the additions are performed left-to-right and  sometext   the first one  is just a const char    It has no operator  to call  The simplest fix is this   std  string var   std  string  sometext     somevar    sometext    somevar    Now  the first parameter in the left-to-right list of   operations is a std  string  which has an operator  const char     That operator produces a string  which makes the rest of the chain work   You can also make all the operations be on var  which is a std  string and so has all the necessary operators   var    sometext   var    somevar  var     sometext   var    somevar

User · Answer

In C  11 you can use std  to string   std  string var    sometext    std  to string somevar     sometext    std  to string somevar

User · Answer

Have you considered using stringstreams    include  lt string gt   include  lt sstream gt   std  ostringstream oss  oss  lt  lt   sometext   lt  lt  somevar  lt  lt   sometext   lt  lt  somevar  std  string var   oss str

User · Answer

You can also use sprintf   char str 1024   sprintf str   somtext  s sometext  s   somevar  somevar

[c++] C++ create string of text and variables

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