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---
title: str2num
---
# The `stdlib_str2num` module
This module proposes a function-style interface for string-to-number conversion. It also profits from Fortran's interfaces to implement precision-dependant algorithms to maximize runtime efficiency.
[TOC]
## `to_num` - conversion of strings to numbers
### Status
Experimental
### Description
Convert a string or an array of strings to numerical types.
### Syntax
`number = ` [[stdlib_str2num(module):to_num(interface)]] `(string, mold)`
### Arguments
`string`: argument has `intent(in)` and is of type `character(*)`.
`mold`: argument has `intent(in)` and is of numerical type (that is of `integer` or of `real`). **Note**: The type of the `mold` argument defines the type of the result.
### Return value
Return a scalar of numerical type (i.e., `integer`, or `real`).
### Example
```fortran
{!example/strings/example_string_to_number.f90!}
```
## `to_num_from_stream` - conversion of a stream of values in a string to numbers
### Status
Experimental
### Description
Convert a stream of values in a string to an array of values.
### Syntax
`number = ` [[stdlib_str2num(module):to_num_from_stream(interface)]] `(string, mold)`
### Arguments
`string`: argument has `intent(in)` and is of type `character(:), pointer`.
`mold`: argument has `intent(in)` and is of numerical type (currently of `integer` or `real`). **Note**: The type of the `mold` argument defines the type of the result.
### Return value
Return a scalar of numerical type (i.e., `integer` or `real`).
### Example
```fortran
{!example/strings/example_stream_of_strings_to_numbers.f90!}
```
## Note
The accuracy of the conversion is implementation dependent; it is recommended that implementers guarantee precision down to the last 3 bits.
**The current implementation has been tested to provide for** :
`sp` : exact match
`dp` : precision up-to epsilon(0.0_dp)
`qp` : precision around 200*epsilon(0.0_qp)
Where precision refers to the relative difference between `to_num` and `read`. On the other hand, `to_num` provides speed-ups ranging from 4x to >10x compared to the intrinsic `read`.
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