我正在尝试逐行读取配置文件,然后将结果标记化并将结果存储到单独的变量中。我的配置文件如下所示
stage 1
num_nodes 2
nonce 234567
我需要分别标记行中的每个值,例如在第一行“阶段”用于检查我是否已从配置文件中读取阶段值,然后将其值保存在变量中。我的标记化似乎工作正常。但是,当我在标记化后尝试操作我的变量时,它会给我一个段错误。我最多只能成功地操纵其中一个变量,即 stage 或 num_nodes 或 nonce,但不能是它们的组合。即使尝试做类似的事情
stage = stage + 1;
num_nodes = num_nodes + 1;
但是,如果我只更改一个变量,例如:
num_nodes = num_nodes + 1;
然后它工作正常。我正在粘贴下面的代码,请告诉我我在这里遗漏了什么。
main(int argc, char *argv[]){
int nonce;
int num_nodes;
int stage;
char filename[256];
char *token1, *token2, *str;
FILE* fp;
char bufr[MAXLINE];
printf("Please enter config file name\n");
scanf("%s",filename);
printf("You entered %s\n", filename);
if((fp = fopen(filename, "r")) != NULL){
while(fgets(bufr, MAXLINE, fp) != NULL){
if(bufr[0] == '#') // to skip comments
continue;
printf("This is bufr: %s", bufr);
str = bufr;
for(str; ;str = NULL){
token1 = strtok(str, " ");
if(strcmp(token2, "num_nodes") == 0){
num_nodes = atoi(token1);
printf("num_nodes = %d\n", num_nodes);
}
if(strcmp(token2, "nonce") == 0){
nonce = atoi(token1);
printf("nonce = %d\n", nonce);
}
if(strcmp(token2, "stage") == 0){
stage = atoi(token1);
printf("stage = %d\n", stage);
}
token2 = token1; // making a copy of pointer
if(str == NULL){
break;
}
}//end of for loop
}//end of while loop
fclose(fp); //close the file handle
}
else{
printf("failed, file not found!\n");
}
/* This is where the segmentation fault kicks in, try to uncomment two lines and it will give a segmentation fault, if uncomment just one, then it works fine.
nonce = nonce + 2;
num_nodes = num_nodes + 1;
printf("stage = %d\n", stage);
*/
}
最佳答案
您的代码包含:
token1 = strtok(str, " ");
if (strcmp(token2, "num_nodes") == 0){
num_nodes = atoi(token1);
printf("num_nodes = %d\n", num_nodes);
}
您刚刚设置了token1
,但是您继续比较token2
?这可能会导致核心转储,至少在第一次从未设置 token2
时是这样。
最后,在循环之后,出现核心转储的唯一原因是您已经在分配的内存范围之外四处乱窜。原因不是很明显,但是循环结构是……奇怪,我们可以说。
这是您的代码的一个清理过的、不会让我崩溃的版本。您的原件还不错,但 token2
的不确定状态令人担忧。一个版本的输出包括如下信息:
Please enter config file name
You entered config.file
This is bufr: # Comment
This is bufr:
This is bufr: stage 1
token1 = <<stage>>; token2 = <<>>
token1 = <<1
>>; token2 = <<stage>>
stage = 1
This is bufr: num_nodes 2
token1 = <<num_nodes>>; token2 = <<des>>
token1 = <<2
>>; token2 = <<num_nodes>>
num_nodes = 2
This is bufr: nonce 234567
token1 = <<nonce>>; token2 = <<67
>>
token1 = <<234567
>>; token2 = <<nonce>>
nonce = 234567
This is bufr:
stage = 1
注意 token2
中残留的碎片。我在下面的代码中进一步清理了它:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
enum { MAXLINE = 4096 };
int main(void)
{
int nonce = -1;
int num_nodes = -1;
int stage = -1;
char filename[256];
char *token1, *token2, *str;
FILE *fp;
char bufr[MAXLINE];
printf("Please enter config file name\n");
scanf("%s", filename);
printf("You entered %s\n", filename);
if ((fp = fopen(filename, "r")) == NULL)
{
printf("failed, file not found!\n");
return(1);
}
while (fgets(bufr, MAXLINE, fp) != NULL)
{
printf("This is bufr: %s", bufr);
if (bufr[0] == '#' || bufr[0] == '\n')
continue;
token2 = "";
for (str = bufr; (token1 = strtok(str, " \n\t")) != 0; str = NULL)
{
printf("token1 = <<%s>>; token2 = <<%s>>\n", token1, token2);
if (strcmp(token2, "num_nodes") == 0) {
num_nodes = atoi(token1);
printf("num_nodes = %d\n", num_nodes);
}
if (strcmp(token2, "nonce") == 0) {
nonce = atoi(token1);
printf("nonce = %d\n", nonce);
}
if (strcmp(token2, "stage") == 0) {
stage = atoi(token1);
printf("stage = %d\n", stage);
}
token2 = token1;
if (str == NULL) /* Terminate after name/value */
break;
}
}
fclose(fp);
nonce = nonce + 2;
num_nodes = num_nodes + 1;
printf("stage = %d\n", stage);
printf("nonce = %d\n", nonce);
printf("nodes = %d\n", num_nodes);
return(0);
}
此代码使用命令行在 Mac OS X 10.8.5 和 GCC 4.8.1 上干净地编译:
gcc -O3 -g -std=c11 -Wall -Wextra -Wmissing-prototypes -Wstrict-prototypes -Wold-style-definition cfg.c -o cfg
给定一个名为 config.file
的输入文件:
# Comment
stage 1
num_nodes 2
nonce 234567
(末尾有一个空行),输出是:
Please enter config file name
You entered config.file
This is bufr: # Comment
This is bufr:
This is bufr: stage 1
token1 = <<stage>>; token2 = <<>>
token1 = <<1>>; token2 = <<stage>>
stage = 1
This is bufr: num_nodes 2
token1 = <<num_nodes>>; token2 = <<>>
token1 = <<2>>; token2 = <<num_nodes>>
num_nodes = 2
This is bufr: nonce 234567
token1 = <<nonce>>; token2 = <<>>
token1 = <<234567>>; token2 = <<nonce>>
nonce = 234567
This is bufr:
stage = 1
nonce = 234569
nodes = 3
关于c - 逐行读取文件并在 C 中使用 strtok(),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/18939449/