C++ :: Multi Condition Function For Char Type

I have always written like a>='0'&&a<='9'&&a>='a'&&a<='z' in loops etc, but no more. Basically add whatever you want to condition, and if you want point a to point b just separate them with a '-' sign. Simply

while(!isCharInside(x,"|a-zA-Z0-9.*/=|-|")){/*code*/}
bool isCharInside(char check,string condition="a-zA-Z*/+=|-|0-9"){
for(unsigned int x=0,z=getLenght(condition);x<z;++x){
if(condition[x+1]=='-'&&(condition[x]!='|'&&condition[x+2]!='|')){
if(condition[x]>condition[x+2])swap(condition[x],condition[x+2]);
for(;condition[x]<=condition[x+2];++condition[x]){if(condition[x]==check)return true;};x+=2;}
else if(check==condition[x])return true;
}
return false;}