@@ -199,25 +199,21 @@ end program demo
199199
200200#### Description
201201
202- Extracts the characters from the defined region of the input string by taking strides.
202+ Extracts the characters from the defined region of the input string by taking strides.
203+ Argument ` first ` and ` last ` defines this region for extraction by function ` slice ` .
204+ Argument ` stride ` defines the magnitude and direction (+/-) of stride to be taken while extraction.
205+ ` stride ` when given invalid value 0, is converted to +1.
203206
204- Deduction Process:
207+ Deduction Process:
205208Function first automatically deduces the optional arguments that are not provided by the user.
206- This process is independent of both input ` string ` and permitted indexes of Fortran.
207- Deduced ` first ` and ` last ` argument take +infinity or -infinity value whereas deduced ` stride ` argument takes +1 or -1 value.
208- 209- Validation Process:
210- Argument ` first ` and ` last ` defines this region for extraction by function ` slice ` .
211- If the defined region is invalid i.e. region contains atleast one invalid index, ` first ` and
212- ` last ` are converted to first and last valid indexes in this defined region respectively,
213- if no valid index exists in this region an empty string is returned.
214- ` stride ` can attain both negative or positive values but when the only invalid value
215- 0 is given, it is converted to 1.
216- 217- Extraction Process:
218- After all this, extraction starts from ` first ` index and takes stride of length ` stride ` .
219- Extraction starts only if ` last ` index is crossable from ` first ` index with stride ` stride `
220- and remains active until ` last ` index is crossed.
209+ Deduced ` first ` and ` last ` argument take +infinity or -infinity value and deduced ` stride ` argument
210+ takes value +1 or -1 depending upon the actual argument(s) provided by the user.
211+ 212+ Extraction Process:
213+ Extraction starts only if ` last ` is crossable from ` first ` with stride of ` stride ` .
214+ Extraction starts from the first valid index in the defined region to take stride of ` stride `
215+ and ends when the last valid index in the defined region is crossed.
216+ If no valid index exists in the defined region, empty string is returned.
221217
222218#### Syntax
223219
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