How can my code react to unexpected inputs in c++? - c++

Question

Newbe so please don't be to harsh, I'll try to explain my problem as well as possible.
I have a longer code, that receives 0, 1, or n, arguments as input.
These inputs are supposed to be strings, however if I run my program like this:
./task2 ^!..;:
I simply get:
bash: !..: event not found
how can I prevent this error, and just print an error message?
This is task2.cpp
#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <array>
#include <functional>
#include <math.h>
#include <stdint.h>
using namespace std;
/// Build suffix array from text.
/// Input is an emtpy suffix array and the text.
/// Output is a suffix array (sorted).
void construct(std::vector<uint32_t>& sa, const std::string& text)
{
if(text.empty()) {
cout << "Text is empty" << endl;
return;
}
if (sa.size()!=0) {
sa.clear();
}
for (uint32_t a = 0; a<text.length(); ++a) {
sa.push_back(a);
}
sort(sa.begin(),sa.end(),[&text] (uint32_t s1, uint32_t s2) {
return(text.substr(s1)<=text.substr(s2));
});
return;
}
//Wir brauchen kein $ am Ende unseres Strings, da wir keinen Suffixbaum aufbauen und wir somit nicht das Problem haben
//werden, dass ein Suffix ein Prefix eines aderen Suffix ist.
/// search for a 'query' string in a suffix array 'sa' build from 'text'.
/// Results are returned in 'hits'.
void findmlr(uint32_t& mlr, const uint32_t L, const uint32_t R, const std::string& query, const std::vector<uint32_t>& sa, const std::string& text) {
uint32_t mlrl = mlr;
uint32_t mlrr = mlr;
/* for L */
for(uint32_t l = mlr; l<query.size(); ++l) {
if (query[mlr] == text[sa[L]+mlrl]) {
mlrl+=1;
}
else{
break;
}
}
/* for R */
for(uint32_t r = mlr; r<query.size(); ++r) {
//cout << query[mlr] << text[sa[R]+mlrr] << endl;
if (query[mlr] == text[sa[R]+mlrr]) {
mlrr+=1;
}
else{
break;
}
}
mlr = min(mlrl,mlrr);
return;
}
void find(std::vector<uint32_t>& hits, const std::string& query, const std::vector<uint32_t>& sa, const std::string& text){
if(hits.size()!=0) {
hits.clear();
}
if (cin.fail()) {
cin.clear();
cout << "unexpected input" << endl;
}
if (text.size()==0) {
cout << "text is empty";
return;
}
else if (query.size()==0) {
cout << "query is empty";
return;
}
/* finding Lp */
uint32_t Lp;
if (query <= text.substr(sa[0])){
Lp = 0;
}
else if (query > text.substr(sa[text.length()-1])){
Lp = text.length();
}
else {
uint32_t L = 0;
uint32_t R = text.length()-1;
uint32_t mlr = 0;
while (R-L > 1) {
uint32_t M = ceil((L+R)/2);
findmlr(mlr,L,R,query,sa,text);
if (query.substr(mlr) <= (text.substr(sa[M]+mlr))) {
R = M;
}
else {
L = M;
}
}
Lp = R;
}
for (uint32_t i = Lp; i < text.length(); ++i) {
if ((text.substr(sa[i])).substr(0,query.length()) == query) {
if(find(hits.begin(), hits.end(), sa[i]) != hits.end()){
//do nothing
}
else{
hits.push_back(sa[i]);
}
}
else {
break;
}
}
sort(hits.begin(), hits.end());
return;
}
and this is task2_main.cpp
#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include "aufgabe2.hpp"
#include <stdint.h>
//#include <typeinfo>
using namespace std;
int main(int argc, char* argv[]){
if (argc < 2){
cout << "not enough arguments were given" << endl;
return 1;}
if (argc == 2){
vector<uint32_t> sa;
string input_string(argv[1]);
construct(sa,input_string);
for(uint32_t i = 0; i<input_string.length(); ++i) {
cout << sa[i] << endl;
}
return 0;
}
if (argc > 2){
vector<uint32_t> hits;
string text(argv[1]);
vector<uint32_t> sa;
if (sa.size() != 0) {
sa.clear();
}
if (hits.size() != 0) {
hits.clear();
}
int z;
z = 2;
while(z < argc){
/*
if(typeid(argv[z])!=typeid(text)) {
cout << typeid(text).name() << z << " is not of type string" << endl;
}
*/
if (sa.size()!=0) {
sa.clear();
}
for (int unsigned a = 0; a<text.length(); ++a)
{
sa.push_back(a);
}
sort(sa.begin(),sa.end(),[&text] (uint32_t s1, uint32_t s2) {
return(text.substr(s1)<=text.substr(s2));
});
string query(argv[z]);
string input_string(argv[1]);
if (query.size() == 0) {
//do nothing
}
else if (input_string.size() == 0) {
//do nothing
}
else {
cout << (argv[z]) << ":";
}
find(hits,query,sa,input_string);
for (uint32_t i = 0; i < hits.size(); ++i) {
cout << " " << hits[i];
}
cout << endl;
++z;
}
}
return 0;
}

Answer 1

"Bash event not found" is completely external to your program; GNU Bash has a (mis)feature whereby it reacts to the ! character in a command line, even if that character is in a double-quote.
$ echo "blah!blah!"
bash: !blah!: event not found
$ echo 'blah!blah!'
blah!blah!
Note that in the first case, echo is not even called; Bash failed to process the command line as such, and echo was never invoked. If you see this message, your program is not being called at all and so the situation doesn't speak to how your program handles any kind of input.
You have to escape the ! with single quotes or a backslash. What Bash is trying to do here is to look for blah in the command history for a command which begins with blah and substitute it. This is "history expansion".
The feature is fully described under HISTORY EXPANSION in the Bash manual page.