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raises Not_found: position = SCAN (string, set «, back» «, kind») position = VERIFY (string, set «, back» «, kind») Fortran: returns zero string indexOf: char ifAbsent: aBlock string indexOf: char string includes: char: Smalltalk: evaluate aBlock which is a BlockClosure (or any object understanding value) returns 0 returns true or false
While simple to implement, this representation has been prone to errors and performance problems. Null-termination has historically created security problems. [6] A NUL inserted into the middle of a string will truncate it unexpectedly. [7] A common bug was to not allocate the additional space for the NUL, so it was written over adjacent memory.
Off-by-one errors are common in using the C library because it is not consistent with respect to whether one needs to subtract 1 byte – functions like fgets() and strncpy will never write past the length given them (fgets() subtracts 1 itself, and only retrieves (length − 1) bytes), whereas others, like strncat will write past the length given them.
A string is defined as a contiguous sequence of code units terminated by the first zero code unit (often called the NUL code unit). [1] This means a string cannot contain the zero code unit, as the first one seen marks the end of the string. The length of a string is the number of code units before the zero code unit. [1]
C programmers draw a sharp distinction between a "string", aka a "string of characters", which by definition is always null terminated, vs. a "array of characters" which may be stored in the same array but is often not null terminated. Using C string handling functions on such an array of characters often seems to work, but later leads to ...
Here is an example of ANSI C code that will generally cause a segmentation fault on platforms with memory protection. It attempts to modify a string literal, which is undefined behavior according to the ANSI C standard. Most compilers will not catch this at compile time, and instead compile this to executable code that will crash:
load a byte or Boolean value from an array bastore 54 0101 0100 arrayref, index, value → store a byte or Boolean value into an array bipush 10 0001 0000 1: byte → value push a byte onto the stack as an integer value: breakpoint ca 1100 1010 reserved for breakpoints in Java debuggers; should not appear in any class file caload 34 0011 0100
C does not provide direct support to exception handling: it is the programmer's responsibility to prevent errors in the first place and test return values from the functions.