cppstring.cpp:57:18: runtime error: load of null pointer of type 'char'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior cppstring.cpp:57:18 in
AddressSanitizer:DEADLYSIGNAL
=================================================================
==16860==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x00010d1a9330 bp 0x7ff7b2d60360 sp 0x7ff7b2d601c0 T0)
==16860==The signal is caused by a READ memory access.
==16860==Hint: address points to the zero page.
    #0 0x10d1a9330 in String::Reserve(unsigned long)+0x550 (a.out:x86_64+0x10000a330)
    #1 0x10d1a8c71 in String::String(unsigned long, char)+0xf1 (a.out:x86_64+0x100009c71)
    #2 0x10d1a9609 in String::String(unsigned long, char)+0x59 (a.out:x86_64+0x10000a609)
    #3 0x10d1a3492 in TestConstructors()+0x1c2 (a.out:x86_64+0x100004492)
    #4 0x10d1a3c1f in main+0x2f (a.out:x86_64+0x100004c1f)
    #5 0x7ff80564c30f  (<unknown module>)

==16860==Register values:
rax = 0x0000000000000000  rbx = 0x00007ff7b2d60200  rcx = 0x0000100000000000  rdx = 0x00007ff7b2d5f4e0
rdi = 0x00007ff7b2d5f4a0  rsi = 0x00007ff7b2d5f4e0  rbp = 0x00007ff7b2d60360  rsp = 0x00007ff7b2d601c0
 r8 = 0x000000010d630380   r9 = 0x000000000000003f  r10 = 0x0000000000000000  r11 = 0x0000000000000206
r12 = 0x000000010d1d0c80  r13 = 0x00007ff7b2d609d0  r14 = 0x000000010d1d0c60  r15 = 0x000000010d1a3bf0
AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV (a.out:x86_64+0x10000a330) in String::Reserve(unsigned long)+0x550
==16860==ABORTING
Abort trap: 6