1 This clause describes components that C++ programs may use to detect and report error conditions.
2 The following subclauses describe components for reporting several kinds of exceptional conditions, documenting program assertions, and a global variable for error number codes, as summarized in Table 24:
| Table 24---Diagnostics library summary |
_ ____________________________________ _ Subclause Header(s) _ ____________________________________ ____________________________________ _ 19.1 Exception classes <stdexcept> ____________________________________ _ 19.2 Assertions <cassert> ____________________________________ _ 19.3 Error numbers <cerrno> ____________________________________ |
1 The Standard C++ library provides classes to be used to report certain errors (17.4.4.8) in C++ programs. In the error model reflected in these classes, errors are divided into two broad categories: logic errors and runtime errors.
2 The distinguishing characteristic of logic errors is that they are due to errors in the internal logic of the program. In theory, they are preventable.
3 By contrast, runtime errors are due to events beyond the scope of the program. They cannot be easily predicted in advance. The header <stdexcept> defines several types of predefined exceptions for reporting errors in a C++ program. These exceptions are related by inheritance. Header <stdexcept> synopsis
namespace std {
class logic_error;
class domain_error;
class invalid_argument;
class length_error;
class out_of_range;
class runtime_error;
class range_error;
class overflow_error;
class underflow_error;
}
namespace std {
class logic_error : public exception {
public:
explicit logic_error(const string& what_arg);
};
}
1 The class logic_error defines the type of objects thrown as exceptions to report errors presumably detectable before the program executes, such as violations of logical preconditions or class invariants.
logic_error(const string& what_arg);
2 Effects: Constructs an object of class logic_error.
3 Postcondition: strcmp(what(), what_arg.c_str()) == 0.
namespace std {
class domain_error : public logic_error {
public:
explicit domain_error(const string& what_arg);
};
}
1 The class domain_error defines the type of objects thrown as exceptions by the implementation to report domain errors.
domain_error(const string& what_arg);
2 Effects: Constructs an object of class domain_error.
3 Postcondition: strcmp(what(), what_arg.c_str()) == 0.
namespace std {
class invalid_argument : public logic_error {
public:
explicit invalid_argument(const string& what_arg);
};
}
1 The class invalid_argument defines the type of objects thrown as exceptions to report an invalid argument.
invalid_argument(const string& what_arg);
2 Effects: Constructs an object of class invalid_argument.
3 Postcondition: strcmp(what(), what_arg.c_str()) == 0.
namespace std {
class length_error : public logic_error {
public:
explicit length_error(const string& what_arg);
};
}
1 The class length_error defines the type of objects thrown as exceptions to report an attempt to produce an object whose length exceeds its maximum allowable size.
length_error(const string& what_arg);
2 Effects: Constructs an object of class length_error.
3 Postcondition: strcmp(what(), what_arg.c_str()) == 0.
namespace std {
class out_of_range : public logic_error {
public:
explicit out_of_range(const string& what_arg);
};
}
1 The class out_of_range defines the type of objects thrown as exceptions to report an argument value not in its expected range.
out_of_range(const string& what_arg);
2 Effects: Constructs an object of class out_of_range.
3 Postcondition: strcmp(what(), what_arg.c_str()) == 0.
namespace std {
class runtime_error : public exception {
public:
explicit runtime_error(const string& what_arg);
};
}
1 The class runtime_error defines the type of objects thrown as exceptions to report errors presumably detectable only when the program executes.
runtime_error(const string& what_arg);
2 Effects: Constructs an object of class runtime_error.
3 Postcondition: strcmp(what(), what_arg.c_str()) == 0.
namespace std {
class range_error : public runtime_error {
public:
explicit range_error(const string& what_arg);
};
}
1 The class range_error defines the type of objects thrown as exceptions to report range errors in internal computations.
range_error(const string& what_arg);
2 Effects: Constructs an object of class range_error.
3 Postcondition: strcmp(what(), what_arg.c_str()) == 0.
namespace std {
class overflow_error : public runtime_error {
public:
explicit overflow_error(const string& what_arg);
};
}
1 The class overflow_error defines the type of objects thrown as exceptions to report an arithmetic overflow error.
overflow_error(const string& what_arg);
2 Effects: Constructs an object of class overflow_error.
3 Postcondition: strcmp(what(), what_arg.c_str()) == 0.
namespace std {
class underflow_error : public runtime_error {
public:
explicit underflow_error(const string& what_arg);
};
}
1 The class underflow_error defines the type of objects thrown as exceptions to report an arithmetic underflow error.
underflow_error(const string& what_arg);
2 Effects: Constructs an object of class underflow_error.
3 Postcondition: strcmp(what(), what_arg.c_str()) == 0.
1 Provides macros for documenting C++ program assertions, and for disabling the assertion checks.
2 Header <cassert> (Table 25):
| Table 25---Header <cassert> synopsis |
_ ____________________ _ Type Name(s) ____________________ _ Macro: assert ____________________ |
3 The contents are the same as the Standard C library header <assert.h>. SEE ALSO: ISO C subclause 7.2.
1 Header <cerrno> (Table 26):
| Table 26---Header <cerrno> synopsis |
_ __________________________________ _ Type Name(s) __________________________________ _ Macros: EDOM ERANGE errno __________________________________ |
2 The contents are the same as the Standard C library header <errno.h>. SEE ALSO: ISO C subclause 7.1.4, 7.2, Amendment 1 subclause 4.3.