Question

现在我尝试使用名为“ GAUL ”的开源工具，其中实现了一些遗传算法。通过编译示例文件，我发现我只能通过使用gcc而不是g ++来编译这些数据。 E.x：

1）使用gcc -I /usr/local/include/ -c wildfire_threat.c -o test.o

gcc** -g -O2 -Wall -o test2.out test.o -lgaul -lgaul_util -lm -lpthread -lslang -lm

也适用于组合

gcc -I /usr/local/include/ -c wildfire_threat.c -o test.o

g++ -g -O2 -Wall -o test2.out test.o -lgaul -lgaul_util -lm -lpthread -lslang -lm

但是2）使用

g++ -I /usr/local/include/ -c wildfire_threat.c -o test.o

g++ -g -O2 -Wall -o test2.out test.o -lgaul -lgaul_util -lm -lpthread -lslang -lm

我收到以下错误消息：

test.o: In function `wildfire_simulation(int*, bool)':
wildfire_threat.c:(.text+0x52): undefined reference to `random_int(unsigned int)'
wildfire_threat.c:(.text+0x74): undefined reference to `random_int(unsigned int)'
test.o: In function `wildfire_score(population_t*, entity_t*)':
wildfire_threat.c:(.text+0xb55): undefined reference to `ga_entity_set_fitness(entity_t*, double)'
test.o: In function `wildfire_seed(population_t*, entity_t*)':
wildfire_threat.c:(.text+0xb86): undefined reference to `random_boolean()'
wildfire_threat.c:(.text+0xbb9): undefined reference to `random_boolean_prob(double)'
wildfire_threat.c:(.text+0xc18): undefined reference to `random_int(unsigned int)'
wildfire_threat.c:(.text+0xc25): undefined reference to `random_int(unsigned int)'
wildfire_threat.c:(.text+0xc92): undefined reference to `random_int(unsigned int)'
test.o: In function `wildfire_mutate_flip(population_t*, entity_t*, entity_t*)': 
wildfire_threat.c:(.text+0xd41): undefined reference to `random_int(unsigned int)'
test.o: In function `wildfire_crossover(population_t*, entity_t*, entity_t*, entity_t*, entity_t*)':
wildfire_threat.c:(.text+0xe25): undefined reference to `random_boolean()' 
wildfire_threat.c:(.text+0xe37): undefined reference to `random_int(unsigned int)' 
wildfire_threat.c:(.text+0xff0): undefined reference to `random_int(unsigned int)'
test.o: In function `wildfire_ga_callback(int, population_t*)':
wildfire_threat.c:(.text+0x11bc): undefined reference to `ga_get_entity_from_rank(population_t*, unsigned int)'
wildfire_threat.c:(.text+0x11c4): undefined reference to `ga_entity_get_fitness(entity_t*)'
wildfire_threat.c:(.text+0x11ef): undefined reference to 
`ga_population_score_and_sort(population_t*)' 
wildfire_threat.c:(.text+0x1206): undefined reference to `ga_fitness_mean_stddev(population_t*, double*, double*)'
wildfire_threat.c:(.text+0x122b): undefined reference to `ga_get_entity_from_rank(population_t*, unsigned int)'
wildfire_threat.c:(.text+0x1233): undefined reference to `ga_entity_get_fitness(entity_t*)'
wildfire_threat.c:(.text+0x1268): undefined reference to `ga_get_entity_from_rank(population_t*, unsigned int)'
wildfire_threat.c:(.text+0x1270): undefined reference to `ga_entity_get_fitness(entity_t*)'
test.o: In function `main':
wildfire_threat.c:(.text+0x12b0): undefined reference to `random_seed(unsigned int)'
wildfire_threat.c:(.text+0x12dd): undefined reference to `ga_select_two_roulette_rebased(population_t*, entity_t**, entity_t**)'
wildfire_threat.c:(.text+0x12e6): undefined reference to `ga_select_one_roulette_rebased(population_t*, entity_t**)'
wildfire_threat.c:(.text+0x132e): undefined reference to `ga_genesis_integer(int, int, int, bool (*)(int, population_t*), bool (*)(int, entity_t*), void (*)(void*), void (*)(void*), bool (*)(population_t*, entity_t*), bool (*)(population_t*, entity_t*), entity_t* (*)(population_t*, entity_t*), bool (*)(population_t*, entity_t**), bool (*)(population_t*, entity_t**, entity_t**), void (*)(population_t*, entity_t*, entity_t*), void (*)(population_t*, entity_t*, entity_t*, entity_t*, entity_t*), void (*)(population_t*, entity_t*), void*)'
wildfire_threat.c:(.text+0x135c): undefined reference to `ga_population_set_parameters(population_t*, ga_scheme_type_t, ga_elitism_type_t, double, double, double)'
wildfire_threat.c:(.text+0x136d): undefined reference to `ga_evolution_threaded(population_t*, int)'
wildfire_threat.c:(.text+0x137e): undefined reference to `ga_get_entity_from_rank(population_t*, unsigned int)'
wildfire_threat.c:(.text+0x1386): undefined reference to `ga_entity_get_fitness(entity_t*)'
wildfire_threat.c:(.text+0x13b5): undefined reference to `ga_get_entity_from_rank(population_t*, unsigned int)'
wildfire_threat.c:(.text+0x1434): undefined reference to `ga_get_entity_from_rank(population_t*, unsigned int)'
wildfire_threat.c:(.text+0x1528): undefined reference to `ga_extinction(population_t*)'
collect2: ld returned 1 exit status

任何人都可以向我解释这个谜，以及如何避免使用gcc，因为这会给我想要嵌入的剩余源代码带来问题吗？

Answer 1

您的第三方C库可能在其标头中缺少extern "C"声明。要解决此问题而不修改第三方标题，只要您#include相关的第三方标题，就可以在C ++源代码中执行此类操作：

extern "C" {
  #include "gaul.h"         // note: I'm just guessing the names of the
  #include "gaul_utils.h"   //       actual header files here...
}

Answer 2

您应该使用C编译器编译C源代码，使用C ++编译器编译C ++源代码。在特定情况下，GAUL库是用C语言编写的，其标题不适合包含在C ++编译中 - 它们缺少extern "C"，所以当你编译为C ++时，函数是用C ++链接声明的，当然，无法在C编译库中找到。

不能使用g ++进行编译

2 个答案: