github.com/benhoyt/goawk@v1.8.1/testdata/gawk/regexprange.awk (about)

     1  BEGIN {
     2  	range = "[a-dx-z]"
     3  
     4  	split("ABCDEFGHIJKLMNOPQRSTUVWXYZ", upper, "")
     5  	split("abcdefghijklmnopqrstuvwxyz", lower, "")
     6  
     7  	for (i = 1; i in upper; i++)
     8  		printf("%s ~ %s ---> %s\n",
     9  			upper[i], range, (upper[i] ~ range) ? "true" : "false")
    10  
    11  	for (i = 1; i in lower; i++)
    12  		printf("%s ~ %s ---> %s\n",
    13  			lower[i], range, (lower[i] ~ range) ? "true" : "false")
    14  }