如何在 c 中显示 printf 语句的行号？答案

【问题标题】：How can I display the line number for a printf statement in c?如何在 c 中显示 printf 语句的行号？
【发布时间】：2016-06-24 12:55:35
【问题描述】：

int main() {
int i, repeatName; // ints
char firstName[50]; // array to store users name

// get first name from user
printf("Please enter your first name: ");
scanf("%s", firstName);

// get amount of times user would like to repeat name
printf("How many times would you like to repeat your name?: ");
scanf("%i", &repeatName);

// tell user name has to be repeated at last one
if (repeatName < 1) {
    printf("The name has to be repeated at least one (1) time. Try again: ");
    scanf("%i", &repeatName);
}

// for loop to repeat name 'x' number of times
for (i = 0; i < repeatName; i++) {
    printf("%s \n", firstName);
}
}

例如：如果用户想显示他们的名字 3 次，它会说：

Your name 

Your name

Your name

我怎么能说出来：

Line 1 Your name

Line 2 Your name

Line 3 Your name

【问题讨论】：

行号后面的标准是什么？只是迭代次数吗？

标签： c printf scanf

【解决方案1】：

使用循环中的i变量作为行号

for (i = 0; i < repeatName; ++i)
    printf("Line %d %s\n", i + 1, firstName);

一定要加 1，因为循环索引从 0 开始。您希望第一行说“Line 1”，而不是“Line 0”，依此类推。

编辑：当行号超过一位时，输出不那么漂亮。为了解决这个问题，你可以写

for (i = 0; i < repeatName; ++i)
    printf("Line %-6d%s\n", i + 1, firstName);

这使得行号占用至少 6 个字符，并使行号左对齐：

Line 1     this is my string
Line 2     this is my string
Line 3     this is my string
Line 4     this is my string
Line 5     this is my string
Line 6     this is my string
Line 7     this is my string
Line 8     this is my string
Line 9     this is my string
Line 10    this is my string

【讨论】：

谢谢！这正是我想要做的。也欣赏编辑。

【解决方案2】：

据我所知，没有办法自动执行此操作。但是你也可以让 for 循环中的 i 变量充当行计数器，因为每次迭代都会打印一行：

// for loop to repeat name 'x' number of times
for (i = 0; i < repeatName; i++) {
    printf("Line %d %s \n", i + 1 /* Lines are not 0 based */ , firstName);
}

【讨论】：

【解决方案3】：

打印时只需添加循环索引：

for (i = 0; i < repeatName; i++) {
    printf("Line %d %s \n", i+1, firstName);
}

【讨论】：

【解决方案4】：

试试这个代码

 #include <stdio.h>
    int main() 
    {
    int i, repeatName; // ints
    char firstName[50]; // array to store users name

    // get first name from user
    printf("Please enter your first name: ");
    scanf("%s", firstName);

    // get amount of times user would like to repeat name
    printf("How many times would you like to repeat your name?: ");
    scanf("%i", &repeatName);

    // tell user name has to be repeated at last one
    if (repeatName < 1) {
        printf("The name has to be repeated at least one (1) time. Try again: ");
        scanf("%i", &repeatName);
    }

    // for loop to repeat name 'x' number of times
    for (i = 1; i <= repeatName; i++) {
        printf("Line %d Your name %s \n",i,firstName);
    }
    }

【讨论】：