OC Basic knowledge--string processing method

Immutable string

"Initialization of OC string"

1. Initialization of strings (subtraction method)

NSString * str2 = [[NSString alloc]init];

2. Initialization of strings (plus method)

NSString * STR3 = [NSString string];

3. Initialization of a string is given by another string

NSString * STR4 = [[NSString ALLOC]INITWITHSTRING:STR1];

4. Give the C-language string The OC string as the initialized value (minus method)

NSString * STR6 = [[NSString alloc]initwithutf8string: "CCCC"];

5. Give the C-language string to the OC string as the initialized value (plus method)

NSString * STR7 = [NSString stringwithutf8string: "CCCCC"];

6. The OC string initialization in a custom format (minus method)

NSString * Str8 = [[NSString alloc]initwithformat:@ "%d%c%@", 2, ' A ', @ "ohhhh~"];

7. The OC string initialization in a custom format (plus method)

NSString * STR9 = [NSString stringwithformat:@ "%d%c%@", 2, ' B ', @ "shabi~~"];

"Turn OC string to other type"

1. Convert string to int type

int i = [str intvalue];

2. Turn string into float type

float f = [str floatvalue];

3. Convert a string to a long long type

Long long L = [str longlongvalue];

4. Convert string to OC Nsuinteger type

Nsuinteger n = [str integervalue];

5. Convert a string to a double type

Double d = [str doublevalue];

6. Convert string to BOOL type

BOOL b = [str boolvalue];

7. Convert a string to a C-language string

const char * p = [str utf8string];

"Comparison of Strings"

1. Compare characters are not the same

BOOL ret = [str1 ISEQUALTOSTRING:STR2];

2. Compare the size of two strings

Nscomparisonresult Ret1 = [str1 compare:str2];

return value:

Nsorderedsame: Equal

Nsordereddescending: Descending (left greater than right)

Nsorderedascending: Ascending (right greater than left)

3. Get the length of the string

Nsuinteger len = [str1 length];

4. Get the first few characters of the OC string

Unichar C = [str1 characteratindex:0];

Traverse:

for (int i = 0; i < len; i + +) {

c = [str1 characteratindex:i];

NSLog (@ "%c", c);

}

"Sub-string"

1. Find the range of substrings in the parent string

Nsrange rang = [str rangeofstring:substr];

/*

typedef struct _NSRANGE {

Nsuinteger location; Index

Nsuinteger length; Length

} Nsrange;

*/

2. Extracting substrings (from index to end of string)

NSString * sub1 = [str substringfromindex:3];

3. Extracting substrings (from the beginning to the index excluding indexes)

NSString * sub2 = [str substringtoindex:3];

4. Extracting a range of substrings

SUB3 = [Str substringwithrange:nsmakerange (1, 4)];

"Case Conversion"

1. Lowercase all turn into uppercase

NSString * St2 = [St1 uppercasestring];

2. Uppercase all to lowercase

NSString * ST3 = [St1 lowercasestring];

"Mutable string"

"Initialize"

1. Initialization of open space (subtraction method)

nsmutablestring * str1 = [[nsmutablestring alloc]initwithcapacity:10];

2. Initialization of open space (plus method)

STR1 = [nsmutablestring stringwithcapacity:10];

3. Initialization of formatted strings

nsmutablestring * str2 = [[nsmutablestring alloc]initwithformat:@ "%@", @ "abc"];

"Variable string additions and deletions" no return value

1. Append

[str2 appendstring:@ "123"];

2. Formatted append

[str2 appendformat:@ "%d%@", 2,@ "ASD"];

3. Remove a range character from a string

[Str2 deletecharactersinrange:nsmakerange (0, 2)];

4. Insert

[str2 insertstring:@ "AAA" atindex:3];

5. Modify

[Str2 Replacecharactersinrange:nsmakerange (3, 4) withstring:@ "Maoge"];

6. Reset

[str2 setstring:@ "ABCD"];

3 Kinds of empty methods delete reset substitution

[Str2 deletecharactersinrange:nsmakerange (0, [str2 length])];

[str2 setstring:@ ""];

[Str2 replacecharactersinrange:nsmakerange (0, [str2 length]) withstring:@ ""];

OC Basic knowledge--string processing method