concatCStr statement

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concatCStr		statement

Syntax 1
concatCStr( targetCString, sourceCString1 [ , sourceCString2 [ ... ] )

Description
The concatCStr statement concatenates two or more C strings into a target C string.
The first argument is the target C string followed by the C strings to be concatenated, each separated by a comma ','

C strings used with concatCStr must be defined as either an array of characters ( i.e. char ) or array of bytes ( i.e. byte )

Note: the one line C string declaration and initialization works both inside functions ( as shown in the example ) and in main.

Example Showing Declaration & Initialization


local fn DoIt

char s1(3)  = 'abc'   // initialize a C string. String must be in single quotes not double quotes.

char s2(3)  = 'def'

char s3(3)  = 'hij'

char s4(10) = ''

byte b1(5)  // just to show it's possible. Not used in this code

concatCStr( s4(0), s1(0), s2(0), s3(0) )

printf @"%s",@s4(0) // prints abcdefhij

end fn



fn DoIt



HandleEvents

Example Showing Declaration without Initialization


char s8(3)  // if string array declared but not initialized, characters must be assigned separately

s8(0) = 65  : s8(1) = _"Y" : s8(2) = _"Z"

printf @"%s",@s8(0)  // prints AYZ



char s5(3)  = 'klm'// declaration & initialization works in main too

char s6(3)  = 'nop'

char s7(3)  = 'qrs'

char s8(10)



concatCStr( s8(0), s5(0), s6(0), s7(0) )

printf @"%s",@s8(0) // prints klmnopqrs



HandleEvents

Combining long strings without the line continuation character "¬"


// Initializer strings have unlimited length but they can't be combined with the line continuation character ( ¬ ) yet.

// Workaround: use concatCStr

char s5(100)  = '0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789'

char s6(100)  = '0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789'

char s7(100)  = 'abcdefghijabcdefghijabcdefghijabcdefghijabcdefghijabcdefghijabcdefghijabcdefghijabcdefghijabcdefghij'

char big(300)



concatCStr( big(0), s5(0), s6(0), s7(0) )



printf @"%s",@big(0) // prints 300 character string. pascal strings can't do this!



HandleEvents

Passing C Strings to a Function


local fn CStringsPassedToMe( cStr1(3) as char, cStr2(3) as char, returnedStr(10) as char )

concatCStr( returnedStr(0), cStr1(0), cStr2(0) )

printf @"returnedStr within CStringsPassedToMe is: %s",@returnedStr(0) // print abcdefhij

end fn



char s1(3)  = 'abc'   // initialize a CStr ( which is a character array )

char s2(3)  = 'def'

char s3(3)  = 'hij' // could put up to 700 but sizes to whatever is provided

char s4(10) = ''



fn CStringsPassedToMe( s1(0), s2(0), s4(0) )

printf @"s4 after returning from CStringsPassedToMe is: %s",@s4(0) // print abcdefhij



HandleEvents

Caveats
[a] C strings can represent only single byte characters - same as pascal strings.
[b] C strings can be any length, unlike pascal strings.
[c] C string arrays do not go stale like objects but follow local and global variable's access rules.
[d] C language offers other ways to define C strings as pointers. These are not available in FB yet.
[e] However, FB can pass( to a function for example ) a pointer to the C string.
[f] Unsigned types ( i.e. unsigned char ) are not available yet.
[g] All the C language library string functions( like fn strlen) are available too.

[h] This is not a complete C string implementation. Don't expect the same syntax FB provides for pascal strings ( yet ).