Extract using sed or grep

Question

I am fairly new to grep and sed commands.How can +50.0 be extracted from Core 0: +50.0°C (high = +80.0°C, crit = +90.0°C) using grep or sed in bash script?

acpitz-virtual-0
Adapter: Virtual device
temp1:        +50.0°C  (crit = +89.0°C)
temp2:        +50.0°C  (crit = +89.0°C)

coretemp-isa-0000
Adapter: ISA adapter
Core 0:       +50.0°C  (high = +80.0°C, crit = +90.0°C)
Core 2:       +47.0°C  (high = +80.0°C, crit = +90.0°C)

Bash Script:

#!/bin/bash

temp=`sed -n '/^Core 0:      $/,/^(high/p' ~/Desktop/sensors.txt`

echo $temp

Answer 1

Using grep -oP (PCRE regex):

grep -oP 'Core 0: +\K[+-]\d+\.\d+' ~/Desktop/sensors.txt
+50.0

Answer 2

grep -e '^Core 0:' [input] | awk '{ print $3 }'

Or alternately, just in awk,

awk '{ r = "^Core 0:" } { if(match($0,r)) { print $3 } }' [input]

Both of these will print the field you seem to be looking for, with the surrounding whitespace eliminated.