Multiple lines string in C

In this quick tutorial, I will show you how to write multiple line string (multiline string) in C programming language.

There are two ways of splitting char * variable in mupltiple lines.

// 👇 first approach
char *str1 = "line 1\n \
line 2";

// 👇 second approach
char *str2 = "line 1\n"
             "line 2";

I like the second one.

It can be useful for printing multple lines in C. Let’s take a look redis source code as an example. Instead of printing multiple lines string like this

/* taken from: https://github.com/antirez/redis/blob/3.2/src/server.c#L3651-L3666 */
void usage(void) {
    fprintf(stderr,"Usage: ./redis-server [/path/to/redis.conf] [options]\n");
    fprintf(stderr,"       ./redis-server - (read config from stdin)\n");
    fprintf(stderr,"       ./redis-server -v or --version\n");
    fprintf(stderr,"       ./redis-server -h or --help\n");
    fprintf(stderr,"       ./redis-server --test-memory <megabytes>\n\n");
    fprintf(stderr,"Examples:\n");
    fprintf(stderr,"       ./redis-server (run the server with default conf)\n");
    fprintf(stderr,"       ./redis-server /etc/redis/6379.conf\n");
    fprintf(stderr,"       ./redis-server --port 7777\n");
    fprintf(stderr,"       ./redis-server --port 7777 --slaveof 127.0.0.1 8888\n");
    fprintf(stderr,"       ./redis-server /etc/myredis.conf --loglevel verbose\n\n");
    fprintf(stderr,"Sentinel mode:\n");
    fprintf(stderr,"       ./redis-server /etc/sentinel.conf --sentinel\n");
    exit(1);
}

I like to write the code like this one

/* Alternative version of https://github.com/antirez/redis/blob/3.2/src/server.c#L3651-L3666 */
void usage(void) {
    fprintf(stderr,
    "Usage: ./redis-server [/path/to/redis.conf] [options]\n"
    "       ./redis-server - (read config from stdin)\n"
    "       ./redis-server -v or --version\n"
    "       ./redis-server -h or --help\n"
    "       ./redis-server --test-memory <megabytes>\n\n"
    "Examples:\n"
    "       ./redis-server (run the server with default conf)\n"
    "       ./redis-server /etc/redis/6379.conf\n"
    "       ./redis-server --port 7777\n"
    "       ./redis-server --port 7777 --slaveof 127.0.0.1 8888\n"
    "       ./redis-server /etc/myredis.conf --loglevel verbose\n\n"
    "Sentinel mode:\n"
    "       ./redis-server /etc/sentinel.conf --sentinel\n");
    exit(1);
}

less typing FTW.