我对2个功能感到困惑。它们似乎采用相同的一组参数（一个可以直接转换为另一个）并且每个都返回一个AST。功能是否做同样的事情？如果没有，我什么时候需要每个？
2的签名：
Z3_ast Z3_mk_forall (Z3_context c,
unsigned weight,
unsigned num_patterns,
Z3_pattern const patterns[],
unsigned num_decls,
Z3_sort const sorts[],
Z3_symbol const decl_names[],
Z3_ast body)
Z3_ast Z3_mk_forall_const (Z3_context c,
unsigned weight,
unsigned num_bound,
Z3_app const bound[],
unsigned num_patterns,
Z3_pattern const patterns[],
Z3_ast body)
答案 0 :(得分：3)
是的，Z3团队提供了多种方法来做同样的事情。主要区别在于Z3_mk_forall_const采用已使用常规机制定义的常量列表，而Z3_mk_forall需要使用Z3_mk_bound创建的绑定变量列表。
哪种机制更易于使用取决于您的具体应用。特别是，在我看来，Z3_mk_forall_const当你想要构建量词的符号数量很少时，Z3_mk_forall会更自然。相反，Z3_mk_forall_const在量词符号的数量可能变化的情况下可能会更自然，在这种情况下，生成一个您将使用索引处理的绑定变量数组是很自然的。
还有其他优点和缺点。例如，请看这个问题：
"How to declare constants to use as bound variables in Z3_mk_forall_const?"
在那个问题中，提问者希望避免在其全局上下文中引入大量变量，这对于使用Z3_mk_forall是必要的。回答者（Christoph）建议使用Z3_mk_forall_const代替，但这也不理想，因为对于嵌套量词，这将导致每个量词被不同地索引。克里斯托夫还在答案中透露，在内部，基于Z3_mk_forall的方法被转化为等同于// g++ --std=c++11 z3-quantifier-support.cpp -I../src/api/ -I../src/api/c++/ libz3.so
#include <stdio.h>
#include "z3.h"
#include <iostream>
#include "z3++.h"
using namespace z3;
/**
* This is by far the most concise and easiest to use if the C++ API is available to you.
*/
void example_cpp_forall() {
context c;
expr a = c.int_const("a");
expr b = c.int_const("b");
expr x = c.int_const("x");
expr axiom = forall(x, implies(x <= a, x < b));
std::cout << "Result obtained using the C++ API with forall:\n" << axiom << "\n\n";
}
/**
* Example using Z3_mk_forall_const. Not as clean as the C++ example, but this was still
* significantly easier for me to get working than the example using Z3_mk_forall().
*/
void example_c_Z3_mk_forall_const() {
// Get the context
Z3_config cfg;
Z3_context ctx;
cfg = Z3_mk_config();
ctx = Z3_mk_context(cfg);
// Declare integers a, b, and x
Z3_sort I = Z3_mk_int_sort(ctx);
Z3_symbol a_S = Z3_mk_string_symbol(ctx, "a");
Z3_symbol b_S = Z3_mk_string_symbol(ctx, "b");
Z3_symbol x_S = Z3_mk_string_symbol(ctx, "x");
Z3_ast a_A = Z3_mk_const(ctx, a_S, I);
Z3_ast b_A = Z3_mk_const(ctx, b_S, I);
Z3_ast x_A = Z3_mk_const(ctx, x_S, I);
// Build the AST (x <= a) --> (x < b)
Z3_ast x_le_a = Z3_mk_le(ctx, x_A, a_A);
Z3_ast x_lt_b = Z3_mk_lt(ctx, x_A, b_A);
Z3_ast f = Z3_mk_implies(ctx, x_le_a, x_lt_b);
Z3_app vars[] = {(Z3_app) x_A};
Z3_ast axiom = Z3_mk_forall_const(ctx, 0, 1, vars, 0, 0, f);
printf("Result obtained using the C API with Z3_mk_forall_const:\n");
printf("%s\n\n", Z3_ast_to_string(ctx, axiom));
}
/**
* Example using Z3_mk_forall. For the example, this is the most cumbersome.
*/
void example_c_Z3_mk_forall() {
// Get the context
Z3_config cfg;
Z3_context ctx;
cfg = Z3_mk_config();
ctx = Z3_mk_context(cfg);
// Declare integers a and b
Z3_sort I = Z3_mk_int_sort(ctx);
Z3_symbol a_S = Z3_mk_string_symbol(ctx, "a");
Z3_symbol b_S = Z3_mk_string_symbol(ctx, "b");
Z3_ast a_A = Z3_mk_const(ctx, a_S, I);
Z3_ast b_A = Z3_mk_const(ctx, b_S, I);
// Declare bound variables, in this case, just x
Z3_symbol x_S = Z3_mk_string_symbol(ctx, "x");
Z3_ast x_A = Z3_mk_bound(ctx, 0, I);
// Z3_mk_forall requires all names, types, and bound variables to be provided in
// arrays. In this example, where there is only one quantified variable, this seems a
// bit cumbersome. If we were dealing with an varying number of quantified variables,
// then this would seem more reasonable.
const unsigned sz = 1;
const Z3_sort types[] = {I};
const Z3_symbol names[] = {x_S};
const Z3_ast xs[] = {x_A};
// Build the AST (x <= a) --> (x < b)
Z3_ast x_le_a = Z3_mk_le(ctx, x_A, a_A);
Z3_ast x_lt_b = Z3_mk_lt(ctx, x_A, b_A);
Z3_ast f = Z3_mk_implies(ctx, x_le_a, x_lt_b);
// In the Z3 docs for Z3_mk_pattern, the following sentence appears: "If a pattern is
// not provided for a quantifier, then Z3 will automatically compute a set of
// patterns for it." So I tried supplying '0' for the number of patterns, and 'NULL'
// for the list of patterns, and Z3_mk_forall still seems to function.
Z3_ast axiom = Z3_mk_forall(ctx, 0, 0, NULL, sz, types, names, f);
printf("Result obtained using the C API with Z3_mk_forall:\n");
printf("%s\n", Z3_ast_to_string(ctx, axiom));
}
int main() {
example_cpp_forall();
example_c_Z3_mk_forall_const();
example_c_Z3_mk_forall();
}
的方法，所以在引擎盖下确实没有区别。但是，API差异会给程序员带来很大的不同。
如果你能够使用它，那么在C ++ API中还为程序员提供了一种（更简单的）机制。以下是使用三种不同方法的示例：
{{1}}
我也发现这些问题很有用：
Z3源中提供的示例和注释也很有帮助，特别是在examples/c/test_capi.c，examples/c++/example.cpp和src/api/z3_api.h中。