How to Use the indexof and substring functions in C #

Indexof (): locates the character and string from the front to the back in the string. All return values are absolute positions in the string. If it is null, it is-1.

String test = "asdfjsdfjgkfasdsfsgfhgjgfjgdddd"; test. indexof (d) = 2 // locate the location where d appears for the first time

Test. indexof (d, 1) = 2 // locate the first position of d from the third string

Test. indexof (d, 5, 2) = 6 // locate d from the front to the back and query it from 5th bits. Check 2 bits, that is, from 5th bits to 7th bits;

Lastindexof (): locates the character and string from the back and forward in the string. The usage and indexof () are identical.
The following describes IndexOfAny | lastindexofany. They accept character arrays as variable elements. The other methods are the same as above. The earliest subscript position of any character in the array is returned as follows:

Char [] bbv = {s, c, B };

String abc = "acsdfgdfgchacstcsad ";

Response. Write (abc. IndexOfAny (bbv) = 1

Response. Write (abc. IndexOfAny (bbv, 5) = 9

Response. Write (abc. IndexOfAny (bbv, 5, 3) = 9 lastindexofany same as above

Substring () Usage

String a = "aadsfdjkfgklfdglfd" a. substring (5) // capture all strings after the fifth digit

A. substring (0th) // capture a string with a length of 5 starting from the position