我是新的C programming.I正在试图通过每行线和打印长度采取从文件线路输入。这是我的code -
I am new to C programming.I am trying to take input from a file line by line and print length of each line. This is my code-
#include<stdio.h> #include<stdlib.h> #include<string.h> int main() { char name[100]; printf("Enter file name\n"); scanf("%s",name); FILE * input; input=fopen(name,"r"); char line[100]; fscanf(input,"%s",line); while(!feof(input)) { printf("%d\n",strlen(line)); fscanf(input,"%s",line); } return 0; }这是我的输入文件 -
This is my input file-
172.24.2.1 172.24.2.225 172.17.4.41 172.24.4.42 202.16.112.150 172.24.152.10这是正确打印编译期间每个line.But的长度,我得到这样的警告 -
This is correctly printing the length of each line.But during compilation I get this warning-
In function ‘main’: main.c:24:4: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘size_t’ [-Wformat=] printf("%d\n",strlen(line));所以我的问题是,为什么我会收到这样的警告,虽然我的输出是正确的,我怎么能解决这个问题?先谢谢了。
So my question is why am I getting this warning although my output is correct and how can I fix this? Thanks in advance.
推荐答案功能的strlen 返回类型的对象为size_t (参见ISO 9899:2011§7.24.6.3)。您需要指定传递给的printf 参数的类型为为size_t ,而不是 INT 。为此,您可以通过添加以Z 长度修改(参见ISO 9899:2011§7.21.6.1/ 7)指定类型为size_t 。你也应该使用 U 格式符为为size_t 是一个无符号类型。
The function strlen returns an object of type size_t (cf. ISO 9899:2011§7.24.6.3). You need to specify that the argument you pass to printf has type size_t, as opposed to int. You can do that by adding a z length modifier (cf. ISO 9899:2011§7.21.6.1/7) specifying an object of type size_t. You should also use the u formatting specifier as size_t is an unsigned type.
printf("%zu\n",strlen(line));更多推荐
使用C中的strlen警告
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